1
|
Chi PF, Chuang YL, Yu Z, Zhang JW, Wang JJ, Lee ML, Sheu JK. Large-area and few-layered 1T'-MoTe 2thin films grown by cold-wall chemical vapor deposition. NANOTECHNOLOGY 2024; 35:415603. [PMID: 38958023 DOI: 10.1088/1361-6528/ad5db7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 07/02/2024] [Indexed: 07/04/2024]
Abstract
This study employs cold-wall chemical vapor deposition to achieve the growth of MoTe2thin films on 4-inch sapphire substrates. A two-step growth process is utilized, incorporating MoO3and Te powder sources under low-pressure conditions to synthesize MoTe2. The resultant MoTe2thin films exhibit a dominant 1T' phase, as evidenced by a prominent Raman peak at 161 cm-1. This preferential 1T' phase formation is attributed to controlled manipulation of the second-step growth temperature, essentially the reaction stage between Te vapor and the pre-deposited MoOxlayer. Under these optimized growth conditions, the thickness of the continuous 1T'-MoTe2films can be precisely tailored within the range of 3.5-5.7 nm (equivalent to 5-8 layers), as determined by atomic force microscopy depth profiling. Hall-effect measurements unveil a typical hole concentration and mobility of 0.2 cm2Vs-1and 7.9 × 1021cm-3, respectively, for the synthesized few-layered 1T'-MoTe2films. Furthermore, Ti/Al bilayer metal contacts deposited on the few-layered 1T'-MoTe2films exhibit low specific contact resistances of approximately 1.0 × 10-4Ω cm2estimated by the transfer length model. This finding suggests a viable approach for achieving low ohmic contact resistance using the 1T'-MoTe2intermediate layer between metallic electrodes and two-dimensional semiconductors.
Collapse
Affiliation(s)
- Ping-Feng Chi
- Department of Photonics, National Cheng Kung University, Tainan City 70101, Taiwan
| | - Yung-Lan Chuang
- Department of Photonics, National Cheng Kung University, Tainan City 70101, Taiwan
| | - Zide Yu
- Department of Photonics, National Cheng Kung University, Tainan City 70101, Taiwan
| | - Jing-Wen Zhang
- Academy of Innovative Semiconductor and Sustainable Manufacturing, National Cheng Kung University, Tainan City 70101, Taiwan
| | - Jing-Jie Wang
- Academy of Innovative Semiconductor and Sustainable Manufacturing, National Cheng Kung University, Tainan City 70101, Taiwan
| | - Ming-Lun Lee
- Department of Electro-Optical Engineering, Southern Taiwan University of Science and Technology, Tainan City 71001, Taiwan
| | - Jinn-Kong Sheu
- Department of Photonics, National Cheng Kung University, Tainan City 70101, Taiwan
- Academy of Innovative Semiconductor and Sustainable Manufacturing, National Cheng Kung University, Tainan City 70101, Taiwan
| |
Collapse
|
2
|
Lin YT, Hsu CH, Chou AS, Fong ZY, Chuu CP, Chang SJ, Hsu YW, Chou SA, Liew SL, Chiu TY, Hou FR, Ni IC, Hou DHV, Cheng CC, Radu IP, Wu CI. Antimony-Platinum Modulated Contact Enabling Majority Carrier Polarity Selection on a Monolayer Tungsten Diselenide Channel. NANO LETTERS 2024; 24:8880-8886. [PMID: 38981026 PMCID: PMC11273612 DOI: 10.1021/acs.nanolett.4c01436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 06/23/2024] [Accepted: 06/24/2024] [Indexed: 07/11/2024]
Abstract
We develop a novel metal contact approach using an antimony (Sb)-platinum (Pt) bilayer to mitigate Fermi-level pinning in 2D transition metal dichalcogenide channels. This strategy allows for control over the transport polarity in monolayer WSe2 devices. By adjustment of the Sb interfacial layer thickness from 10 to 30 nm, the effective work function of the contact/WSe2 interface can be tuned from 4.42 eV (p-type) to 4.19 eV (n-type), enabling selectable n-/p-FET operation in enhancement mode. The shift in effective work function is linked to Sb-Se bond formation and an emerging n-doping effect. This work demonstrates high-performance n- and p-FETs with a single WSe2 channel through Sb-Pt contact modulation. After oxide encapsulation, the maximum current density at |VD| = 1 V reaches 170 μA/μm for p-FET and 165 μA/μm for n-FET. This approach shows promise for cost-effective CMOS transistor applications using a single channel material and metal contact scheme.
Collapse
Affiliation(s)
- Yu-Tung Lin
- Graduate
Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 106, Taiwan
- Corporate
Research, Taiwan Semiconductor Manufacturing
Company, Hsinchu 30091, Taiwan
| | - Ching-Hao Hsu
- Graduate
Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 106, Taiwan
- Corporate
Research, Taiwan Semiconductor Manufacturing
Company, Hsinchu 30091, Taiwan
| | - Ang-Sheng Chou
- Corporate
Research, Taiwan Semiconductor Manufacturing
Company, Hsinchu 30091, Taiwan
| | - Zi-Yun Fong
- Graduate
Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 106, Taiwan
| | - Chih-Piao Chuu
- Corporate
Research, Taiwan Semiconductor Manufacturing
Company, Hsinchu 30091, Taiwan
| | - Shu-Jui Chang
- Corporate
Research, Taiwan Semiconductor Manufacturing
Company, Hsinchu 30091, Taiwan
| | - Yu-Wei Hsu
- Graduate
Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 106, Taiwan
| | - Sui-An Chou
- Corporate
Research, Taiwan Semiconductor Manufacturing
Company, Hsinchu 30091, Taiwan
| | - San Lin Liew
- Quality
& Reliability, Taiwan Semiconductor
Manufacturing Company, Hsinchu 30091, Taiwan
| | - Ting-Ying Chiu
- Graduate
Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 106, Taiwan
| | - Fa-Rong Hou
- Graduate
Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 106, Taiwan
| | - I-Chih Ni
- Graduate
Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 106, Taiwan
| | - Duen-Huei Vincent Hou
- Quality
& Reliability, Taiwan Semiconductor
Manufacturing Company, Hsinchu 30091, Taiwan
| | - Chao-Ching Cheng
- Corporate
Research, Taiwan Semiconductor Manufacturing
Company, Hsinchu 30091, Taiwan
| | - Iuliana P. Radu
- Corporate
Research, Taiwan Semiconductor Manufacturing
Company, Hsinchu 30091, Taiwan
| | - Chih-I Wu
- Graduate
Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 106, Taiwan
| |
Collapse
|
3
|
Yang Q, Wang YP, Shi XL, Li X, Zhao E, Chen ZG, Zou J, Leng K, Cai Y, Zhu L, Pantelides ST, Lin J. Constrained patterning of orientated metal chalcogenide nanowires and their growth mechanism. Nat Commun 2024; 15:6074. [PMID: 39025911 PMCID: PMC11258352 DOI: 10.1038/s41467-024-50525-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 07/13/2024] [Indexed: 07/20/2024] Open
Abstract
One-dimensional metallic transition-metal chalcogenide nanowires (TMC-NWs) hold promise for interconnecting devices built on two-dimensional (2D) transition-metal dichalcogenides, but only isotropic growth has so far been demonstrated. Here we show the direct patterning of highly oriented Mo6Te6 NWs in 2D molybdenum ditelluride (MoTe2) using graphite as confined encapsulation layers under external stimuli. The atomic structural transition is studied through in-situ electrical biasing the fabricated heterostructure in a scanning transmission electron microscope. Atomic resolution high-angle annular dark-field STEM images reveal that the conversion of Mo6Te6 NWs from MoTe2 occurs only along specific directions. Combined with first-principles calculations, we attribute the oriented growth to the local Joule-heating induced by electrical bias near the interface of the graphite-MoTe2 heterostructure and the confinement effect generated by graphite. Using the same strategy, we fabricate oriented NWs confined in graphite as lateral contact electrodes in the 2H-MoTe2 FET, achieving a low Schottky barrier of 11.5 meV, and low contact resistance of 43.7 Ω µm at the metal-NW interface. Our work introduces possible approaches to fabricate oriented NWs for interconnections in flexible 2D nanoelectronics through direct metal phase patterning.
Collapse
Affiliation(s)
- Qishuo Yang
- Department of Physics and Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen, People's Republic of China
- Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area (Guangdong), Shenzhen, People's Republic of China
- School of Mechanical and Mining Engineering, The University of Queensland Brisbane, Qld, Australia
| | - Yun-Peng Wang
- School of Physics and Electronics, Hunan Key Laboratory for Super-Micro Structure and Ultrafast Process, Central South University, Changsha, People's Republic of China
| | - Xiao-Lei Shi
- School of Chemistry and Physics, Queensland University of Technology Brisbane, Qld, Australia
| | - XingXing Li
- Department of Physics and Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen, People's Republic of China
| | - Erding Zhao
- Department of Physics and Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen, People's Republic of China
| | - Zhi-Gang Chen
- School of Chemistry and Physics, Queensland University of Technology Brisbane, Qld, Australia
| | - Jin Zou
- Center for Microscopy and Microanalysis, The University of Queensland Brisbane, St Lucia, Qld, Australia
| | - Kai Leng
- Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Yongqing Cai
- Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau, SAR, China
| | - Liang Zhu
- Department of Physics and Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen, People's Republic of China.
| | - Sokrates T Pantelides
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, USA
- Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, TN, USA
| | - Junhao Lin
- Department of Physics and Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen, People's Republic of China.
- Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area (Guangdong), Shenzhen, People's Republic of China.
| |
Collapse
|
4
|
Xie J, Zhang Z, Zhang H, Nagarajan V, Zhao W, Kim HL, Sanborn C, Qi R, Chen S, Kahn S, Watanabe K, Taniguchi T, Zettl A, Crommie MF, Analytis J, Wang F. Low Resistance Contact to P-Type Monolayer WSe 2. NANO LETTERS 2024; 24:5937-5943. [PMID: 38712885 DOI: 10.1021/acs.nanolett.3c04195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Advanced microelectronics in the future may require semiconducting channel materials beyond silicon. Two-dimensional (2D) semiconductors, with their atomically thin thickness, hold great promise for future electronic devices. One challenge to achieving high-performance 2D semiconductor field effect transistors (FET) is the high contact resistance at the metal-semiconductor interface. In this study, we develop a charge-transfer doping strategy with WSe2/α-RuCl3 heterostructures to achieve low-resistance ohmic contact for p-type monolayer WSe2 transistors. We show that hole doping as high as 3 × 1013 cm-2 can be achieved in the WSe2/α-RuCl3 heterostructure due to its type-III band alignment, resulting in an ohmic contact with resistance of 4 kΩ μm. Based on that, we demonstrate p-type WSe2 transistors with an on-current of 35 μA·μm-1 and an ION/IOFF ratio exceeding 109 at room temperature.
Collapse
Affiliation(s)
- Jingxu Xie
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Graduate Group in Applied Science and Technology, University of California at Berkeley, Berkeley, California 94720, United States
- Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Zuocheng Zhang
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Haodong Zhang
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Vikram Nagarajan
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Wenyu Zhao
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Ha-Leem Kim
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Collin Sanborn
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Ruishi Qi
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Sudi Chen
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Salman Kahn
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Alex Zettl
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli Energy NanoSciences Institute at University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Michael F Crommie
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli Energy NanoSciences Institute at University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - James Analytis
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli Energy NanoSciences Institute at University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Feng Wang
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli Energy NanoSciences Institute at University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| |
Collapse
|
5
|
Meng J, Lee C, Li Z. Adjustment methods of Schottky barrier height in one- and two-dimensional semiconductor devices. Sci Bull (Beijing) 2024; 69:1342-1352. [PMID: 38490891 DOI: 10.1016/j.scib.2024.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 01/10/2024] [Accepted: 02/02/2024] [Indexed: 03/17/2024]
Abstract
The Schottky contact which is a crucial interface between semiconductors and metals is becoming increasingly significant in nano-semiconductor devices. A Schottky barrier, also known as the energy barrier, controls the depletion width and carrier transport across the metal-semiconductor interface. Controlling or adjusting Schottky barrier height (SBH) has always been a vital issue in the successful operation of any semiconductor device. This review provides a comprehensive overview of the static and dynamic adjustment methods of SBH, with a particular focus on the recent advancements in nano-semiconductor devices. These methods encompass the work function of the metals, interface gap states, surface modification, image-lowering effect, external electric field, light illumination, and piezotronic effect. We also discuss strategies to overcome the Fermi-level pinning effect caused by interface gap states, including van der Waals contact and 1D edge metal contact. Finally, this review concludes with future perspectives in this field.
Collapse
Affiliation(s)
- Jianping Meng
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, China; School of Nanoscience and Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Chengkuo Lee
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; Center for Intelligent Sensors and MEMS, National University of Singapore, Singapore 117608, Singapore.
| | - Zhou Li
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, China; School of Nanoscience and Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
| |
Collapse
|
6
|
Sorkin V, Zhou H, Yu ZG, Ang KW, Zhang YW. An Atomically Resolved Schottky Barrier Height Approach for Bridging the Gap between Theory and Experiment at Metal-Semiconductor Heterojunctions. ACS APPLIED MATERIALS & INTERFACES 2024; 16:22166-22176. [PMID: 38648115 DOI: 10.1021/acsami.4c02294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
We propose an atomically resolved approach to capture the spatial variations of the Schottky barrier height (SBH) at metal-semiconductor heterojunctions. This proposed scheme, based on atom-specific partial density of states (PDOS) calculations, further enables calculation of the effective SBH that aligns with conductance measurements. We apply this approach to study the variations of SBH at MoS2@Au heterojunctions, in which MoS2 contains conducting and semiconducting grain boundaries (GBs). Our results reveal that there are significant variations in SBH at atoms in the defected heterojunctions. Of particular interest is the fact that the SBH in some areas with extended defects approaches zero, indicating Ohmic contact. One important implication of this finding is that the effective SBH should be intrinsically dependent on the defect density and character. Remarkably, the obtained effective SBH values demonstrate good agreement with existing experimental measurements. Thus, the present study addresses two long-standing challenges associated with SBH in MoS2-metal heterojunctions: the wide variation in experimentally measured SBH values at MoS2@metal heterojunctions and the large discrepancy between density-functional-theory-predicted and experimentally measured SBH values. Our proposed approach points out a valuable pathway for understanding and manipulating SBHs at metal-semiconductor heterojunctions.
Collapse
Affiliation(s)
- Viacheslav Sorkin
- Agency for Science, Technology and Research (A*STAR), Institute of High Performance Computing (IHPC), 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Republic of Singapore
| | - Hangbo Zhou
- Agency for Science, Technology and Research (A*STAR), Institute of High Performance Computing (IHPC), 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Republic of Singapore
| | - Zhi Gen Yu
- Agency for Science, Technology and Research (A*STAR), Institute of High Performance Computing (IHPC), 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Republic of Singapore
| | - Kah-Wee Ang
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Republic of Singapore
| | - Yong-Wei Zhang
- Agency for Science, Technology and Research (A*STAR), Institute of High Performance Computing (IHPC), 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Republic of Singapore
| |
Collapse
|
7
|
Liu B, Yue X, Sheng C, Chen J, Tang C, Shan Y, Han J, Shen S, Wu W, Li L, Lu Y, Hu L, Liu R, Qiu ZJ, Cong C. High-Performance Contact-Doped WSe 2 Transistors Using TaSe 2 Electrodes. ACS APPLIED MATERIALS & INTERFACES 2024; 16:19247-19253. [PMID: 38591143 DOI: 10.1021/acsami.4c01605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
Two-dimensional (2D) transitional metal dichalcogenides (TMDs) have garnered significant attention due to their potential for next-generation electronics, which require device scaling. However, the performance of TMD-based field-effect transistors (FETs) is greatly limited by the contact resistance. This study develops an effective strategy to optimize the contact resistance of WSe2 FETs by combining contact doping and 2D metallic electrode materials. The contact regions were doped using a laser, and the metallic TaSe2 flakes were stacked on doped WSe2 as electrodes. Doping the contact areas decreases the depletion width, while introducing the TaSe2 contact results in a lower Schottky barrier. This method significantly improves the electrical performance of the WSe2 FETs. The doped WSe2/TaSe2 contact exhibits an ultralow Schottky barrier height of 65 meV and a contact resistance of 11 kΩ·μm, which is a 50-fold reduction compared to the conventional Cr/Au contact. Our method offers a way on fabricating high-performance 2D FETs.
Collapse
Affiliation(s)
- Bingjie Liu
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Xiaofei Yue
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Chenxu Sheng
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Jiajun Chen
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Chengjie Tang
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Yabing Shan
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Jinkun Han
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Shuwen Shen
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Wenxuan Wu
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Lijia Li
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Ye Lu
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Laigui Hu
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Ran Liu
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Zhi-Jun Qiu
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Chunxiao Cong
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
- Yiwu Research Institute of Fudan University, Yiwu, Zhejiang 322000, China
| |
Collapse
|
8
|
Geng H, Tang J, Wu Y, Yu Y, Guest JR, Zhang R. Imaging Valley Excitons in a 2D Semiconductor with Scanning Tunneling Microscope-Induced Luminescence. ACS NANO 2024; 18:8961-8970. [PMID: 38470346 DOI: 10.1021/acsnano.3c12555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
Valley excitons dominate the optoelectronic response of transition-metal dichalcogenides and are drastically affected by structural and environmental inhomogeneities localized in these materials. Critical to understanding and controlling these nanoscale excitonic changes is the ability to correlate the imaging of excitonic states with crystalline structures on the atomic scale. Here, we apply scanning tunneling microscope-induced luminescence microscopy to image valley excitons in a semiconducting transition-metal dichalcogenide monolayer decoupled by a 10 nanometer-thick hexagonal-boron-nitride flake incorporated in a lateral homojunction on an Au electrode surface. This design enables the observation of chiral excitonic emission arising from neutral and charged valley excitons of the monolayer semiconductor at ambipolar voltages with a quantum efficiency up to ∼10-5 photon/electron. The measured light helicity demonstrates considerable circular polarization dependent on the sample voltage, reaching as much as 40%. The real-space luminescence imaging maps─at subnanometer resolution─of the valley excitons reveal striking spatial variations associated with localized inhomogeneities, including surface impurities and possibly nanoscale dielectric and/or potential disorders in the monolayer. Our study introduces a promising format for 2D materials to explore and tailor their optoelectronic processes at the atomic scale.
Collapse
Affiliation(s)
- Hairui Geng
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
| | - Jie Tang
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
| | - Yanwei Wu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
| | - Yuanqin Yu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
| | - Jeffrey R Guest
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Rui Zhang
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Optoelectronic Information Acquisition and Manipulation, Ministry of Education, School of Physics and Optoelectronics Engineering, Anhui University, Hefei Anhui 230601, China
| |
Collapse
|
9
|
Ma L, Wang Y, Liu Y. van der Waals Contact for Two-Dimensional Transition Metal Dichalcogenides. Chem Rev 2024; 124:2583-2616. [PMID: 38427801 DOI: 10.1021/acs.chemrev.3c00697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2024]
Abstract
Two-dimensional (2D) transition metal dichalcogenides (TMDs) have emerged as highly promising candidates for next-generation electronics owing to their atomically thin structures and surfaces devoid of dangling bonds. However, establishing high-quality metal contacts with TMDs presents a critical challenge, primarily attributed to their ultrathin bodies and delicate lattices. These distinctive characteristics render them susceptible to physical damage and chemical reactions when conventional metallization approaches involving "high-energy" processes are implemented. To tackle this challenge, the concept of van der Waals (vdW) contacts has recently been proposed as a "low-energy" alternative. Within the vdW geometry, metal contacts can be physically laminated or gently deposited onto the 2D channel of TMDs, ensuring the formation of atomically clean and electronically sharp contact interfaces while preserving the inherent properties of the 2D TMDs. Consequently, a considerable number of vdW contact devices have been extensively investigated, revealing unprecedented transport physics or exceptional device performance that was previously unachievable. This review presents recent advancements in vdW contacts for TMD transistors, discussing the merits, limitations, and prospects associated with each device geometry. By doing so, our purpose is to offer a comprehensive understanding of the current research landscape and provide insights into future directions within this rapidly evolving field.
Collapse
Affiliation(s)
- Likuan Ma
- Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education, School of Physics and Electronics, Hunan University, Changsha 410082, China
| | - Yiliu Wang
- Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education, School of Physics and Electronics, Hunan University, Changsha 410082, China
| | - Yuan Liu
- Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education, School of Physics and Electronics, Hunan University, Changsha 410082, China
| |
Collapse
|
10
|
Yoon H, Lee S, Seo J, Sohn I, Jun S, Hong S, Im S, Nam Y, Kim HJ, Lee Y, Chung SM, Kim H. Investigation on Contact Properties of 2D van der Waals Semimetallic 1T-TiS 2/MoS 2 Heterojunctions. ACS APPLIED MATERIALS & INTERFACES 2024; 16:12095-12105. [PMID: 38384197 DOI: 10.1021/acsami.3c18982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Two-dimensional transition metal dichalcogenides (2D TMDCs) are considered promising alternatives to Si as channel materials because of the possibility of retaining their superior electronic transport properties even at atomic body thicknesses. However, the realization of high-performance 2D TMDC field-effect transistors remains a challenge owing to Fermi-level pinning (FLP) caused by gap states and the inherent high Schottky barrier height (SBH) within the metal contact and channel layer. This study demonstrates that high-quality van der Waals (vdW) heterojunction-based contacts can be formed by depositing semimetallic TiS2 onto monolayer (ML) MoS2. After confirming the successful formation of a TiS2/ML MoS2 heterojunction, the contact properties of vdW semimetal TiS2 were thoroughly investigated. With clean interfaces of the TiS2/ML MoS2 heterojunctions, atomic-layer-deposited TiS2 can induce gap-state saturation and suppress FLP. Consequently, compared with conventional evaporated metal electrodes, the TiS2/ML MoS2 heterojunctions exhibit a lower SBH of 8.54 meV and better contact properties. This, in turn, substantially improves the overall performance of the device, including its on-current, subthreshold swing, and threshold voltage. Furthermore, we believe that our proposed strategy for vdW-based contact formation will contribute to the development of 2D materials used in next-generation electronics.
Collapse
Affiliation(s)
- Hwi Yoon
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Sangyoon Lee
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Jeongwoo Seo
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Inkyu Sohn
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Sukhwan Jun
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Sungjae Hong
- van der Waals Materials Research Center, Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
| | - Seongil Im
- van der Waals Materials Research Center, Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
| | - Yunyong Nam
- Samsung Display Co., Ltd, Yongin-si, Gyeonggi-do 17113, Republic of Korea
| | - Hyung-Jun Kim
- Samsung Display Co., Ltd, Yongin-si, Gyeonggi-do 17113, Republic of Korea
| | - Yujin Lee
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - Seung-Min Chung
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Hyungjun Kim
- School of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, Republic of Korea
| |
Collapse
|
11
|
Hossen MF, Shendokar S, Aravamudhan S. Defects and Defect Engineering of Two-Dimensional Transition Metal Dichalcogenide (2D TMDC) Materials. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:410. [PMID: 38470741 DOI: 10.3390/nano14050410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 02/04/2024] [Accepted: 02/18/2024] [Indexed: 03/14/2024]
Abstract
As layered materials, transition metal dichalcogenides (TMDCs) are promising two-dimensional (2D) materials. Interestingly, the characteristics of these materials are transformed from bulk to monolayer. The atomically thin TMDC materials can be a good alternative to group III-V and graphene because of their emerging tunable electrical, optical, and magnetic properties. Although 2D monolayers from natural TMDC materials exhibit the purest form, they have intrinsic defects that limit their application. However, the synthesis of TMDC materials using the existing fabrication tools and techniques is also not immune to defects. Additionally, it is difficult to synthesize wafer-scale TMDC materials for a multitude of factors influencing grain growth mechanisms. While defect engineering techniques may reduce the percentage of defects, the available methods have constraints for healing defects at the desired level. Thus, this holistic review of 2D TMDC materials encapsulates the fundamental structure of TMDC materials, including different types of defects, named zero-dimensional (0D), one-dimensional (1D), and two-dimensional (2D). Moreover, the existing defect engineering methods that relate to both formation of and reduction in defects have been discussed. Finally, an attempt has been made to correlate the impact of defects and the properties of these TMDC materials.
Collapse
Affiliation(s)
- Moha Feroz Hossen
- Joint School of Nanoscience and Nanoengineering, 2907 E Gate City Blvd, Greensboro, NC 27401, USA
- Department of Nanoengineering, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA
| | - Sachin Shendokar
- Joint School of Nanoscience and Nanoengineering, 2907 E Gate City Blvd, Greensboro, NC 27401, USA
- Department of Nanoengineering, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA
| | - Shyam Aravamudhan
- Joint School of Nanoscience and Nanoengineering, 2907 E Gate City Blvd, Greensboro, NC 27401, USA
- Department of Nanoengineering, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA
| |
Collapse
|
12
|
Cao Z, Zhao Y, Wu G, Cho J, Abid M, Choi M, Ó Coileáin C, Hung KM, Chang CR, Wu HC. Enhanced NO 2 Sensitivity of Vertically Stacked van der Waals Heterostructure Gas Sensor and Its Remarkable Electric and Mechanical Tunability. ACS APPLIED MATERIALS & INTERFACES 2024; 16:9495-9505. [PMID: 38334441 DOI: 10.1021/acsami.3c17194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Nanodevices based on van der Waals heterostructures have been predicted, and shown, to have unprecedented operational principles and functionalities that hold promise for highly sensitive and selective gas sensors with rapid response times and minimal power consumption. In this study, we fabricated gas sensors based on vertical MoS2/WS2 van der Waals heterostructures and investigated their gas sensing capabilities. Compared with individual MoS2 or WS2 gas sensors, the MoS2/WS2 van der Waals heterostructure gas sensors are shown to have enhanced sensitivity, faster response times, rapid recovery, and a notable selectivity, especially toward NO2. In combination with a theoretical model, we show that it is important to take into account created trapped states (flat bands) induced by the adsorption of gas molecules, which capture charges and alter the inherent built-in potential of van der Waals heterostructure gas sensors. Additionally, we note that the performance of these MoS2/WS2 heterostructure gas sensors could be further enhanced using electrical gating and mechanical strain. Our findings highlight the importance of understanding the effects of altered built-in potentials arising from gas molecule adsorption induced flat bands, thus offering a way to enhance the gas sensing performance of van der Waals heterostructure gas sensors.
Collapse
Affiliation(s)
- Ze Cao
- School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Yue Zhao
- School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Gang Wu
- School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Jiung Cho
- Western Seoul Center, Korea Basic Science Institute, Seoul 03579, Republic of Korea
- Department of Advanced Materials Engineering, Chung-Ang University, 4726, Seodong-daero, Daedeok-myeon, Anseong-si, Gyeonggi-do 17546, Republic of Korea
| | - Mohamed Abid
- School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Miri Choi
- Chuncheon Center, Korea Basic Science Institute, Chuncheon 24341, Republic of Korea
| | - Cormac Ó Coileáin
- Institute of Physics, Faculty of Electrical Engineering and Information Technology, University of the Bundeswehr Munich, Neubiberg 85577, Germany
| | - Kuan-Ming Hung
- Department of Electronics Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 807, Taiwan, ROC
| | - Ching-Ray Chang
- Quantum information center, Chung Yuan Christian University, Taoyuan 32023, Taiwan, ROC
- Department of Physics, National Taiwan University, Taipei 106, Taiwan, ROC
| | - Han-Chun Wu
- School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China
| |
Collapse
|
13
|
Xu K, Holbrook M, Holtzman LN, Pasupathy AN, Barmak K, Hone JC, Rosenberger MR. Validating the Use of Conductive Atomic Force Microscopy for Defect Quantification in 2D Materials. ACS NANO 2023; 17:24743-24752. [PMID: 38095969 DOI: 10.1021/acsnano.3c05056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
Defects significantly affect the electronic, chemical, mechanical, and optical properties of two-dimensional (2D) materials. Thus, it is critical to develop a method for convenient and reliable defect quantification. Scanning transmission electron microscopy (STEM) and scanning tunneling microscopy (STM) possess the required atomic resolution but have practical disadvantages. Here, we benchmark conductive atomic force microscopy (CAFM) by a direct comparison with STM in the characterization of transition metal dichalcogenides (TMDs). The results conclusively demonstrate that CAFM and STM image identical defects, giving results that are equivalent both qualitatively (defect appearance) and quantitatively (defect density). Further, we confirm that CAFM can achieve single-atom resolution, similar to that of STM, on both bulk and monolayer samples. The validation of CAFM as a facile and accurate tool for defect quantification provides a routine and reliable measurement that can complement other standard characterization techniques.
Collapse
Affiliation(s)
- Kaikui Xu
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Madisen Holbrook
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Luke N Holtzman
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
| | - Abhay N Pasupathy
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Katayun Barmak
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
| | - James C Hone
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Matthew R Rosenberger
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| |
Collapse
|
14
|
Madhurantakam S, Mathew G, David BE, Naqvi A, Prasad S. Recent Progress in Transition Metal Dichalcogenides for Electrochemical Biomolecular Detection. MICROMACHINES 2023; 14:2139. [PMID: 38138308 PMCID: PMC10745343 DOI: 10.3390/mi14122139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/08/2023] [Accepted: 11/18/2023] [Indexed: 12/24/2023]
Abstract
Advances in the field of nanobiotechnology are largely due to discoveries in the field of materials. Recent developments in the field of electrochemical biosensors based on transition metal nanomaterials as transducer elements have been beneficial as they possess various functionalities that increase surface area and provide well-defined active sites to accommodate elements for rapid detection of biomolecules. In recent years, transition metal dichalcogenides (TMDs) have become the focus of interest in various applications due to their considerable physical, chemical, electronic, and optical properties. It is worth noting that their unique properties can be modulated by defect engineering and morphology control. The resulting multifunctional TMD surfaces have been explored as potential capture probes for the rapid and selective detection of biomolecules. In this review, our primary focus is to delve into the synthesis, properties, design, and development of electrochemical biosensors that are based on transition metal dichalcogenides (TMDs) for the detection of biomolecules. We aim to explore the potential of TMD-based electrochemical biosensors, identify the challenges that need to be overcome, and highlight the opportunities for further future development.
Collapse
Affiliation(s)
| | | | | | | | - Shalini Prasad
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX 75248, USA; (S.M.)
| |
Collapse
|
15
|
Cai J, Sun Z, Wu P, Tripathi R, Lan HY, Kong J, Chen Z, Appenzeller J. High-Performance Complementary Circuits from Two-Dimensional MoTe 2. NANO LETTERS 2023. [PMID: 37976291 DOI: 10.1021/acs.nanolett.3c03184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
Two-dimensional (2D) materials hold great promise for future complementary metal-oxide semiconductor (CMOS) technology. However, the lack of effective methods to tune the Schottky barrier poses a challenge in constructing high-performance complementary circuits from the same material. Here, we reveal that the polarity of pristine MoTe2 field-effect transistors (FETs) with minimized air exposure is n-type, irrespective of the metal contact type. The fabricated n-FETs with palladium contact can reach electron currents up to 275 μA/μm at VDS = 2 V. For p-FETs, we introduce a novel nitric oxide doping strategy, allowing a controlled transition of MoTe2 FETs from n-type to unipolar p-type. By doping only in the contact region, we demonstrate hole currents up to 170 μA/μm at VDS= -2 V with preserved Ion/Ioff ratios of 105. Finally, we present a complementary inverter circuit comprising the high-performance n- and p-type FETs based on MoTe2, promoting the application of 2D materials in future electronic systems.
Collapse
Affiliation(s)
- Jun Cai
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Zheng Sun
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Peng Wu
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Rahul Tripathi
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Hao-Yu Lan
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jing Kong
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Zhihong Chen
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Joerg Appenzeller
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| |
Collapse
|
16
|
Shi J, Zhao R, Yang Z, Yang J, Zhang W, Wang C, Zhang J. Template-free scalable growth of vertically-aligned MoS 2 nanowire array meta-structural films towards robust superlubricity. MATERIALS HORIZONS 2023; 10:4148-4162. [PMID: 37395527 DOI: 10.1039/d3mh00677h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Two-dimensional (2D) molybdenum disulfide exhibits a variety of intriguing behaviors depending on its orientation layers. Therefore, developing a template-free atomic layer orientation controllable growth approach is of great importance. Here, we demonstrate scalable, template-free, well-ordered vertically-oriented MoS2 nanowire arrays (VO-MoS2 NWAs) embedded in an Ag-MoS2 matrix, directly grown on various substrates (Si, Al, and stainless steel) via one-step sputtering. In the meta-structured film, vertically-standing few-layered MoS2 NWAs of almost micron length (∼720 nm) throughout the entire film bulk. While near the surface, MoS2 lamellae are oriented in parallel, which are beneficial for caging the bonds dangling from the basal planes. Owing to the unique T-type topological characteristics, chemically inert Ag@MoS2 nano-scrolls (NSCs) and nano-crystalline Ag (nc-Ag) nanoparticles (NPs) are in situ formed under the sliding shear force. Thus, incommensurate contact between (002) basal planes and nc-Ag NPs is observed. As a result, robust superlubricity (friction coefficient μ = 0.0039) under humid ambient conditions is reached. This study offers an unprecedented strategy for controlling the basal plane orientation of 2D transition metal dichalcogenides (TMDCs) via substrate independence, using a one-step solution-free easily scalable process without the need for a template, which promotes the potential applications of 2D TMDCs in solid superlubricity.
Collapse
Affiliation(s)
- Jing Shi
- College of Mechanical & Electrical Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi 710021, China
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Runqiang Zhao
- College of Mechanical & Electrical Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi 710021, China
| | - Zaixiu Yang
- Key Laboratory of Science and Technology on Wear and Protection of Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
| | - Jinzhu Yang
- School of Materials Science and Engineering, Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China.
| | - Wenhe Zhang
- School of Materials Science and Engineering, Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China.
| | - Chengbing Wang
- School of Materials Science and Engineering, Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China.
| | - Junyan Zhang
- Key Laboratory of Science and Technology on Wear and Protection of Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
| |
Collapse
|
17
|
Su ZC, Lin CF. Overcoming the Fermi-Level Pinning Effect in the Nanoscale Metal and Silicon Interface. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2193. [PMID: 37570511 PMCID: PMC10420943 DOI: 10.3390/nano13152193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 07/17/2023] [Accepted: 07/26/2023] [Indexed: 08/13/2023]
Abstract
Silicon-based photodetectors are attractive as low-cost and environmentally friendly optical sensors. Also, their compatibility with complementary metal-oxide-semiconductor (CMOS) technology is advantageous for the development of silicon photonics systems. However, extending optical responsivity of silicon-based photodetectors to the mid-infrared (mid-IR) wavelength range remains challenging. In developing mid-IR infrared Schottky detectors, nanoscale metals are critical. Nonetheless, one key factor is the Fermi-level pinning effect at the metal/silicon interface and the presence of metal-induced gap states (MIGS). Here, we demonstrate the utilization of the passivated surface layer on semiconductor materials as an insulating material in metal-insulator-semiconductor (MIS) contacts to mitigate the Fermi-level pinning effect. The removal of Fermi-level pinning effectively reduces the Schottky barrier height by 12.5% to 16%. The demonstrated devices exhibit a high responsivity of up to 234 μA/W at a wavelength of 2 μm, 48.2 μA/W at 3 μm, and 1.75 μA/W at 6 μm. The corresponding detectivities at 2 and 3 μm are 1.17 × 108 cm Hz1/2 W-1 and 2.41 × 107 cm Hz1/2 W-1, respectively. The expanded sensing wavelength range contributes to the application development of future silicon photonics integration platforms.
Collapse
Affiliation(s)
- Zih-Chun Su
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan;
| | - Ching-Fuh Lin
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan;
- Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan
- Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan
| |
Collapse
|
18
|
Hong S, Hong CU, Lee S, Jang M, Jang C, Lee Y, Widiapradja LJ, Park S, Kim K, Son YW, Yook JG, Im S. Ultrafast van der Waals diode using graphene quantum capacitance and Fermi-level depinning. SCIENCE ADVANCES 2023; 9:eadh9770. [PMID: 37467332 DOI: 10.1126/sciadv.adh9770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Accepted: 06/16/2023] [Indexed: 07/21/2023]
Abstract
Graphene, with superior electrical tunabilities, has arisen as a multifunctional insertion layer in vertically stacked devices. Although the role of graphene inserted in metal-semiconductor junctions has been well investigated in quasi-static charge transport regime, the implication of graphene insertion at ultrahigh frequencies has rarely been considered. Here, we demonstrate the diode operation of vertical Pt/n-MoSe2/graphene/Au assemblies at ~200-GHz cutoff frequency (fC). The electric charge modulation by the inserted graphene becomes essentially frozen above a few GHz frequencies due to graphene quantum capacitance-induced delay, so that the Ohmic graphene/MoSe2 junction may be transformed to a pinning-free Schottky junction. Our diodes exhibit much lower total capacitance than devices without graphene insertion, deriving an order of magnitude higher fC, which clearly demonstrates the merit of graphene at high frequencies.
Collapse
Affiliation(s)
- Sungjae Hong
- Department of Physics, Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Chang-Ui Hong
- Department of Electrical Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Sol Lee
- Department of Physics, Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
| | - Myeongjin Jang
- Department of Physics, Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
| | - Chorom Jang
- Department of Electrical Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Yangjin Lee
- Department of Physics, Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
| | - Livia Janice Widiapradja
- Department of Physics, Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Sam Park
- Department of Physics, Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Kwanpyo Kim
- Department of Physics, Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
| | - Young-Woo Son
- School of Computational Sciences, Korea Institute for Advanced Study, Seoul 02455, Republic of Korea
| | - Jong-Gwan Yook
- Department of Electrical Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Seongil Im
- Department of Physics, Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| |
Collapse
|
19
|
Li Z, Zheng Y, Li G, Wang H, Zhu W, Wang H, Chen Z, Yuan Y, Zeng XC, Wu Y. Resolving Interface Barrier Deviation from the Schottky-Mott Rule: A Mitigation Strategy via Engineering MoS 2-Metal van der Waals Contact. J Phys Chem Lett 2023; 14:2940-2949. [PMID: 36930804 DOI: 10.1021/acs.jpclett.3c00056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The Schottky barrier (SB) in the ultraclean van der Waals contact between two-dimensional (2D) MoS2 and three-dimensional (3D) indium (In) strikingly deviates from the Schottky-Mott limit (SML). Herein, on the basis of first-principles calculation, the origin of the SB deviation is brought to bear, as well as a strategy for mitigating the SB deviation. In light of the good agreement between the SB and the corrected SB by interface potential difference (ΔV) and Fermi -level shift (ΔEF) based on the SML, the SB deviation is attributed to the combined effects of ΔV and ΔEF. Furthermore, when a Au, Sc, or Ti thin film is coated on the back side of In, the SB deviation and the sum of ΔV and ΔEF decrease similarly. Importantly, in the Ti coating situation, the SB is reduced to 0.12 eV, notably smaller than the value of 0.30 eV in the Au coating case. This interface engineering can be generalized to regulate the SB between a 2D semiconductor and a 3D alloy.
Collapse
Affiliation(s)
- Zhongjun Li
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Shanxi University, Taiyuan 030006, China
| | - Yahui Zheng
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
| | - Guojun Li
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
| | - Hanxi Wang
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
| | - Weiduo Zhu
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
| | - Haidi Wang
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
| | - Zhao Chen
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
| | - Yupeng Yuan
- School of Materials Science and Engineering, Anhui University, Hefei 2300601, Anhui, China
| | - Xiao Cheng Zeng
- Department of Materials Science & Engineering, City University of Hong Kong, Kowloon 999077, Hong Kong, China
- Department of Chemistry, University of Nebraska─Lincoln, Lincoln, Nebraska 68588, United States
| | - Yucheng Wu
- School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
| |
Collapse
|
20
|
Kumar J, Shrivastava M. Role of Chalcogen Defect Introducing Metal-Induced Gap States and Its Implications for Metal-TMDs' Interface Chemistry. ACS OMEGA 2023; 8:10176-10184. [PMID: 36969396 PMCID: PMC10034985 DOI: 10.1021/acsomega.2c07489] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 02/17/2023] [Indexed: 06/18/2023]
Abstract
The contact resistance of the transition metal dichalcogenide (TMD) devices is not comparable to that of their silicon counterparts, probably due to a lack of clarity in their interface chemistry. Looking beyond the conventional Schottky-Mott rule, the metal chalcogen orbital overlaps, tunnel barrier, and metal-induced gap states (MIGSs) are crucial factors determining different metals' contact properties with TMDs. Exploring their properties helps TMDs' contact resistance engineering, driven mainly by their orbital overlaps and perturbing parameters. This work presents the interface chemistry of TMDs (MoS2, MoSe2, WS2, and WSe2) with different metals (Au, Cr, Ni, and Pd) in detail using density functional theory computations. Additionally, the work discusses the role of the chalcogen vacancy and interstitial defects in the metal-TMD interactions and corresponding MIGS features. The investigations reveal that Au does not show any significant MIGS due to its weak interactions with all the TMDs. However, other investigated metals have a strong affinity with TMDs, making significant MIGS contributions. All the metals offer n-type doping characteristics to TMDs due to valence charge transfer from the metals toward TMDs. The chalcogen vacancy boosts the orbital overlaps of the TMDs with all the metals. The vacancy reduces metal-TMD interfacial distance, which can be a promising technique to reduce the tunnel barrier and contact resistance. The MIGS and defect-induced gap states (DIGSs) reflect the possibility of Fermi-level pinning in the TMDs' contacts with Cr, Ni, and Pd. Besides, the work discloses that the chalcogen vacancy converts an n-type Pd-TMD interface into p-type due to reverse charge transfer after the vacancy. Chalcogen interstitial impurity also helps with contact resistance engineering for some metal-TMD systems by reducing the bond distance of the metal TMDs. Our study highlights the possibility of defect-assisted and MIGS-based contact engineering at the metal-TMD interfaces.
Collapse
|
21
|
Ho PH, Chang JR, Chen CH, Hou CH, Chiang CH, Shih MC, Hsu HC, Chang WH, Shyue JJ, Chiu YP, Chen CW. Hysteresis-Free Contact Doping for High-Performance Two-Dimensional Electronics. ACS NANO 2023; 17:2653-2660. [PMID: 36716244 DOI: 10.1021/acsnano.2c10631] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Contact doping is considered crucial for reducing the contact resistance of two-dimensional (2D) transistors. However, a process for achieving robust contact doping for 2D electronics is lacking. Here, we developed a two-step doping method for effectively doping 2D materials through a defect-repairing process. The method achieves strong and hysteresis-free doping and is suitable for use with the most widely used transition-metal dichalcogenides. Through our method, we achieved a record-high sheet conductance (0.16 mS·sq-1 without gating) of monolayer MoS2 and a high mobility and carrier concentration (4.1 × 1013 cm-2). We employed our robust method for the successful contact doping of a monolayer MoS2 Au-contact device, obtaining a contact resistance as low as 1.2 kΩ·μm. Our method represents an effective means of fabricating high-performance 2D transistors.
Collapse
Affiliation(s)
- Po-Hsun Ho
- Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan
- Center of Atomic Initiative for New Materials, National Taiwan University, Taipei 106, Taiwan
| | - Jun-Ru Chang
- Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan
| | - Chun-Hsiang Chen
- Department of Physics, National Taiwan University, Taipei 106, Taiwan
| | - Cheng-Hung Hou
- Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Chun-Hao Chiang
- Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan
| | - Min-Chuan Shih
- Department of Physics, National Taiwan University, Taipei 106, Taiwan
| | - Hung-Chang Hsu
- Department of Physics, National Taiwan University, Taipei 106, Taiwan
| | - Wen-Hao Chang
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Jing-Jong Shyue
- Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Ya-Ping Chiu
- Center of Atomic Initiative for New Materials, National Taiwan University, Taipei 106, Taiwan
- Department of Physics, National Taiwan University, Taipei 106, Taiwan
| | - Chun-Wei Chen
- Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan
- Center of Atomic Initiative for New Materials, National Taiwan University, Taipei 106, Taiwan
| |
Collapse
|
22
|
Pradhan NR, Garcia C, Chakrabarti B, Rosenmann D, Divan R, Sumant AV, Miller S, Hilton D, Karaiskaj D, McGill SA. Insulator-to-metal phase transition in a few-layered MoSe 2 field effect transistor. NANOSCALE 2023; 15:2667-2673. [PMID: 36652441 DOI: 10.1039/d2nr05019f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The metal-to-insulator phase transition (MIT) in low-dimensional materials and particularly two-dimensional layered semiconductors is exciting to explore due to the fact that it challenges the prediction that a two-dimensional system must be insulating at low temperatures. Thus, the exploration of MITs in 2D layered semiconductors expands the understanding of the underlying physics. Here we report the MIT of a few-layered MoSe2 field effect transistor under a gate bias (electric field) applied perpendicular to the MoSe2 layers. With low applied gate voltage, the conductivity as a function of temperature from 150 K to 4 K shows typical semiconducting to insulating character. Above a critical applied gate voltage, Vc, the conductivity becomes metallic (i.e., the conductivity increases continuously as a function of decreasing temperature). Evidence of a metallic state was observed using an applied gate voltage or, equivalently, increasing the density of charge carriers within the 2D channel. We analyzed the nature of the phase transition using percolation theory, where conductivity scales with the density of charge carriers as σ ∝ (n - nc)δ. The critical exponent for a percolative phase transition, δ(T), has values ranging from 1.34 (at T = 150 K) to 2 (T = 20 K), which is close to the theoretical value of 1.33 for percolation to occur. Thus we conclude that the MIT in few-layered MoSe2 is driven by charge carrier percolation. Furthermore, the conductivity does not scale with temperature, which is a hallmark of a quantum critical phase transition.
Collapse
Affiliation(s)
- Nihar R Pradhan
- Layered Materials and Device Physics Laboratory, Department of Chemistry, Physics and Atmospheric Science, Jackson State University, Jackson, MS 39217, USA.
- National High Magnetic Field Laboratory, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA.
| | - Carlos Garcia
- National High Magnetic Field Laboratory, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA.
- Department of Physics, Florida State University, 77 Chieftan Way, Tallahassee, FL 32306, USA
| | - Bhaswar Chakrabarti
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 S-Cass Avenue, Lemont, IL-60439, USA
- Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai, Tamil Nadu-600036, India
| | - Daniel Rosenmann
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 S-Cass Avenue, Lemont, IL-60439, USA
| | - Ralu Divan
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 S-Cass Avenue, Lemont, IL-60439, USA
| | - Anirudha V Sumant
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 S-Cass Avenue, Lemont, IL-60439, USA
| | - Suzanne Miller
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 S-Cass Avenue, Lemont, IL-60439, USA
| | - David Hilton
- Department of Physics, Baylor University, One Bear Place 97316, Waco, TX 76798-7316, USA
| | - Denis Karaiskaj
- Department of Physics, University of South Florida, Tampa, FL 33620, USA
| | - Stephen A McGill
- National High Magnetic Field Laboratory, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA.
| |
Collapse
|
23
|
Lee M, Kim TW, Park CY, Lee K, Taniguchi T, Watanabe K, Kim MG, Hwang DK, Lee YT. Graphene Bridge Heterostructure Devices for Negative Differential Transconductance Circuit Applications. NANO-MICRO LETTERS 2022; 15:22. [PMID: 36580180 PMCID: PMC9800667 DOI: 10.1007/s40820-022-01001-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 12/11/2022] [Indexed: 06/17/2023]
Abstract
Two-dimensional van der Waals (2D vdW) material-based heterostructure devices have been widely studied for high-end electronic applications owing to their heterojunction properties. In this study, we demonstrate graphene (Gr)-bridge heterostructure devices consisting of laterally series-connected ambipolar semiconductor/Gr-bridge/n-type molybdenum disulfide as a channel material for field-effect transistors (FET). Unlike conventional FET operation, our Gr-bridge devices exhibit non-classical transfer characteristics (humped transfer curve), thus possessing a negative differential transconductance. These phenomena are interpreted as the operating behavior in two series-connected FETs, and they result from the gate-tunable contact capacity of the Gr-bridge layer. Multi-value logic inverters and frequency tripler circuits are successfully demonstrated using ambipolar semiconductors with narrow- and wide-bandgap materials as more advanced circuit applications based on non-classical transfer characteristics. Thus, we believe that our innovative and straightforward device structure engineering will be a promising technique for future multi-functional circuit applications of 2D nanoelectronics.
Collapse
Affiliation(s)
- Minjong Lee
- Department of Electrical and Computer Engineering, Inha University, Incheon, 22212, Republic of Korea
- Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Tae Wook Kim
- Center for Opto-Electronic Materials and Devices, Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Chang Yong Park
- Department of Electrical and Computer Engineering, Inha University, Incheon, 22212, Republic of Korea
| | - Kimoon Lee
- Department of Physics, Kunsan National University, Gunsan, 54150, Republic of Korea
| | - Takashi Taniguchi
- Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, 305-0044, Japan
| | - Kenji Watanabe
- Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, 305-0044, Japan
| | - Min-Gu Kim
- Department of Electrical and Computer Engineering, Inha University, Incheon, 22212, Republic of Korea.
- Department of Information and Communication Engineering, Inha University, Incheon, 22212, Republic of Korea.
| | - Do Kyung Hwang
- Center for Opto-Electronic Materials and Devices, Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea.
- Division of Nanoscience and Technology, KIST School, University of Science and Technology (UST), Seoul, 02792, Republic of Korea.
| | - Young Tack Lee
- Department of Electrical and Computer Engineering, Inha University, Incheon, 22212, Republic of Korea.
- Department of Electronic Engineering, Inha University, Incheon, 22212, Republic of Korea.
| |
Collapse
|
24
|
Birkhölzer YA, Sotthewes K, Gauquelin N, Riekehr L, Jannis D, van der Minne E, Bu Y, Verbeeck J, Zandvliet HJW, Koster G, Rijnders G. High-Strain-Induced Local Modification of the Electronic Properties of VO 2 Thin Films. ACS APPLIED ELECTRONIC MATERIALS 2022; 4:6020-6028. [PMID: 36588623 PMCID: PMC9798830 DOI: 10.1021/acsaelm.2c01176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 11/07/2022] [Indexed: 06/17/2023]
Abstract
Vanadium dioxide (VO2) is a popular candidate for electronic and optical switching applications due to its well-known semiconductor-metal transition. Its study is notoriously challenging due to the interplay of long- and short-range elastic distortions, as well as the symmetry change and the electronic structure changes. The inherent coupling of lattice and electronic degrees of freedom opens the avenue toward mechanical actuation of single domains. In this work, we show that we can manipulate and monitor the reversible semiconductor-to-metal transition of VO2 while applying a controlled amount of mechanical pressure by a nanosized metallic probe using an atomic force microscope. At a critical pressure, we can reversibly actuate the phase transition with a large modulation of the conductivity. Direct tunneling through the VO2-metal contact is observed as the main charge carrier injection mechanism before and after the phase transition of VO2. The tunneling barrier is formed by a very thin but persistently insulating surface layer of the VO2. The necessary pressure to induce the transition decreases with temperature. In addition, we measured the phase coexistence line in a hitherto unexplored regime. Our study provides valuable information on pressure-induced electronic modifications of the VO2 properties, as well as on nanoscale metal-oxide contacts, which can help in the future design of oxide electronics.
Collapse
Affiliation(s)
- Yorick A. Birkhölzer
- MESA+
Institute of Nanotechnology, University
of Twente, P.O. Box 217, 7500AEEnschede, The Netherlands
| | - Kai Sotthewes
- MESA+
Institute of Nanotechnology, University
of Twente, P.O. Box 217, 7500AEEnschede, The Netherlands
| | - Nicolas Gauquelin
- Electron
Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020Antwerp, Belgium
| | - Lars Riekehr
- Electron
Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020Antwerp, Belgium
| | - Daen Jannis
- Electron
Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020Antwerp, Belgium
| | - Emma van der Minne
- MESA+
Institute of Nanotechnology, University
of Twente, P.O. Box 217, 7500AEEnschede, The Netherlands
| | - Yibin Bu
- MESA+
Institute of Nanotechnology, University
of Twente, P.O. Box 217, 7500AEEnschede, The Netherlands
| | - Johan Verbeeck
- Electron
Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020Antwerp, Belgium
| | - Harold J. W. Zandvliet
- MESA+
Institute of Nanotechnology, University
of Twente, P.O. Box 217, 7500AEEnschede, The Netherlands
| | - Gertjan Koster
- MESA+
Institute of Nanotechnology, University
of Twente, P.O. Box 217, 7500AEEnschede, The Netherlands
| | - Guus Rijnders
- MESA+
Institute of Nanotechnology, University
of Twente, P.O. Box 217, 7500AEEnschede, The Netherlands
| |
Collapse
|
25
|
Schram T, Sutar S, Radu I, Asselberghs I. Challenges of Wafer-Scale Integration of 2D Semiconductors for High-Performance Transistor Circuits. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2109796. [PMID: 36071023 DOI: 10.1002/adma.202109796] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 07/01/2022] [Indexed: 06/15/2023]
Abstract
Large-area 2D-material-based devices may find applications as sensor or photonics devices or can be incorporated in the back end of line (BEOL) to provide additional functionality. The introduction of highly scaled 2D-based circuits for high-performance logic applications in production is projected to be implemented after the Si-sheet-based CFET devices. Here, a view on the requirements needed for full wafer integration of aggressively scaled 2D-based logic circuits, the status of developments, and the definition of the gaps to be bridged is provided. Today, typical test vehicles for 2D devices are single-sheet devices fully integrated in a lab environment, but transfer to a more scaled device in a fab environment has been demonstrated. This work reviews the status of the module development, including considerations for setting up fab-compatible process routes for single-sheet devices. While further development on key modules is still required, substantial progress is made for MX2 channel growth, high-k dielectric deposition, and contact engineering. Finally, the process requirements for building ultra-scaled stacked nanosheets are also reflected on.
Collapse
Affiliation(s)
- Tom Schram
- Imec, kapeldreef 75, Heverlee, B7001, Belgium
| | | | | | | |
Collapse
|
26
|
Adam T, Dhahi TS, Gopinath SCB, Hashim U. Novel Approaches in Fabrication and Integration of Nanowire for Micro/Nano Systems. Crit Rev Anal Chem 2022; 52:1913-1929. [DOI: 10.1080/10408347.2021.1925523] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Tijjani Adam
- Faculty of Electronic Engineering Technology, Universiti Malaysia Perlis, Perlis, Malaysia
- Institute of Nano Electronic Engineering, Universiti Malaysia Perlis, Perlis, Malaysia
| | | | - Subash C. B. Gopinath
- Institute of Nano Electronic Engineering, Universiti Malaysia Perlis, Perlis, Malaysia
- Faculty of Chemical Engineering Technology, Universiti Malaysia Perlis, Perlis, Malaysia
| | - Uda Hashim
- Institute of Nano Electronic Engineering, Universiti Malaysia Perlis, Perlis, Malaysia
| |
Collapse
|
27
|
The effects of point defect type, location, and density on the Schottky barrier height of Au/MoS 2 heterojunction: a first-principles study. Sci Rep 2022; 12:18001. [PMID: 36289283 PMCID: PMC9606307 DOI: 10.1038/s41598-022-22913-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 10/20/2022] [Indexed: 12/02/2022] Open
Abstract
Using DFT calculations, we investigate the effects of the type, location, and density of point defects in monolayer MoS2 on electronic structures and Schottky barrier heights (SBH) of Au/MoS2 heterojunction. Three types of point defects in monolayer MoS2, that is, S monovacancy, S divacancy and MoS (Mo substitution at S site) antisite defects, are considered. The following findings are revealed: (1) The SBH for the monolayer MoS2 with these defects is universally higher than that for its defect-free counterpart. (2) S divacancy and MoS antisite defects increase the SBH to a larger extent than S monovacancy. (3) A defect located in the inner sublayer of MoS2, which is adjacent to Au substrate, increases the SBH to a larger extent than that in the outer sublayer of MoS2. (4) An increase in defect density increases the SBH. These findings indicate a large variation of SBH with the defect type, location, and concentration. We also compare our results with previously experimentally measured SBH for Au/MoS2 contact and postulate possible reasons for the large differences among existing experimental measurements and between experimental measurements and theoretical predictions. The findings and insights revealed here may provide practical guidelines for modulation and optimization of SBH in Au/MoS2 and similar heterojunctions via defect engineering.
Collapse
|
28
|
Wu Z, Zhu Y, Wang F, Ding C, Wang Y, Zhan X, He J, Wang Z. Lowering Contact Resistances of Two-Dimensional Semiconductors by Memristive Forming. NANO LETTERS 2022; 22:7094-7103. [PMID: 36053055 DOI: 10.1021/acs.nanolett.2c02136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Two-dimensional semiconductors have great potential for beyond-silicon electronics. However, because of the lack of controllable doping methods, Fermi level pinning, and van der Waals (vdW) gaps at the metal-semiconductor interfaces, these devices exhibit high electrical contact resistances, restricting their practical applications. Here, we report a general contact-resistance-lowering strategy by constructing vertical metal-semiconductor-metal memristor structures at the contact regions and setting them into a nonvolatile low-resistance state through a memristive forming process. Through this, we reduce the contact resistances of MoS2 field-effect transistors (FETs) by at least one order of magnitude and improve the on-state current densities of MoTe2 FETs by about two orders of magnitude. We also demonstrate that this strategy is applicable to other two-dimensional semiconductors, including MoSe2, WS2, and WSe2, and a variety of contact metals, including Au, Cu, Ni, and Pd. The good stability and universality indicate the great potential for technological applications.
Collapse
Affiliation(s)
- Zilong Wu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuhan Zhu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Feng Wang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Chuyun Ding
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, China
- Department of Physics, Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090, China
| | - Yanrong Wang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xueying Zhan
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Jun He
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072, China
| | - Zhenxing Wang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
29
|
Advancement and Challenges of Biosensing Using Field Effect Transistors. BIOSENSORS 2022; 12:bios12080647. [PMID: 36005043 PMCID: PMC9405812 DOI: 10.3390/bios12080647] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/04/2022] [Accepted: 08/08/2022] [Indexed: 11/21/2022]
Abstract
Field-effect transistors (FETs) have become eminent electronic devices for biosensing applications owing to their high sensitivity, faster response and availability of advanced fabrication techniques for their production. The device physics of this sensor is now well understood due to the emergence of several numerical modelling and simulation papers over the years. The pace of advancement along with the knowhow of theoretical concepts proved to be highly effective in detecting deadly pathogens, especially the SARS-CoV-2 spike protein of the coronavirus with the onset of the (coronavirus disease of 2019) COVID-19 pandemic. However, the advancement in the sensing system is also accompanied by various hurdles that degrade the performance. In this review, we have explored all these challenges and how these are tackled with innovative approaches, techniques and device modifications that have also raised the detection sensitivity and specificity. The functional materials of the device are also structurally modified towards improving the surface area and minimizing power dissipation for developing miniaturized microarrays applicable in ultra large scale integration (ULSI) technology. Several theoretical models and simulations have also been carried out in this domain which have given a deeper insight on the electron transport mechanism in these devices and provided the direction for optimizing performance.
Collapse
|
30
|
Sun Y, Jiao Z, Zandvliet HJW, Bampoulis P. Strong Fermi-Level Pinning in GeS-Metal Nanocontacts. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:11400-11406. [PMID: 35865793 PMCID: PMC9289947 DOI: 10.1021/acs.jpcc.2c02827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Germanium sulfide (GeS) is a layered monochalcogenide semiconductor with a band gap of about 1.6 eV. To verify the suitability of GeS for field-effect-based device applications, a detailed understanding of the electronic transport mechanisms of GeS-metal junctions is required. In this work, we have used conductive atomic force microscopy (c-AFM) to study charge carrier injection in metal-GeS nanocontacts. Using contact current-voltage spectroscopy, we identified three dominant charge carrier injection mechanisms: thermionic emission, direct tunneling, and Fowler-Nordheim tunneling. In the forward-bias regime, thermionic emission is the dominating current injection mechanism, whereas in the reverse-bias regime, the current injection mechanism is quantum mechanical tunneling. Using tips of different materials (platinum, n-type-doped silicon, and highly doped p-type diamond), we found that the Schottky barrier is almost independent of the work function of the metallic tip, which is indicative of a strong Fermi-level pinning. This strong Fermi-level pinning is caused by charged defects and impurities.
Collapse
|
31
|
Fabrication of near-invisible solar cell with monolayer WS 2. Sci Rep 2022; 12:11315. [PMID: 35787666 PMCID: PMC9253307 DOI: 10.1038/s41598-022-15352-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 06/22/2022] [Indexed: 11/08/2022] Open
Abstract
Herein, we developed a near-invisible solar cell through a precise control of the contact barrier between an indium tin oxide (ITO) electrode and a monolayer tungsten disulfide (WS2), grown by chemical vapor deposition (CVD). The contact barrier between WS2 and ITO was controlled by coating various thin metals on top of ITO (Mx/ITO) and inserting a thin layer of WO3 between Mx/ITO and the monolayer WS2, which resulted in a drastic increase in the Schottky barrier height (up to 220 meV); this could increase the efficiency of the charge carrier separation in our Schottky-type solar cell. The power conversion efficiency (PCE) of the solar cell with the optimized electrode (WO3/Mx/ITO) was more than 1000 times that of a device using a normal ITO electrode. Large-scale fabrication of the solar cell was also investigated, which revealed that a simple size expansion with large WS2 crystals and parallel long electrodes could not improve the total power (PT) obtained from the complete device even with an increase in the device area; this can be explained by the percolation theory. This problem was addressed by reducing the aspect ratio (width/channel length) of the unit device structure to a value lower than a critical threshold. By repeating the experiments on this optimized unit device with an appropriate number of series and parallel connections, PT could be increased up to 420 pW from a 1-cm2 solar cell with a very high value (79%) of average visible transmission (AVT).
Collapse
|
32
|
Singh A, Price CC, Shenoy VB. Magnetic Order, Electrical Doping, and Charge-State Coupling at Amphoteric Defect Sites in Mn-Doped 2D Semiconductors. ACS NANO 2022; 16:9452-9460. [PMID: 35617052 DOI: 10.1021/acsnano.2c02387] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Two-dimensional (2D) dilute magnetic semiconductors (DMSs) are attractive material platforms for applications in multifunctional nanospintronics due to the prospect of embedding controllable magnetic order within nanoscale semiconductors. Identifying candidate host material and dopant systems requires consideration of doping formation energies, magnetic ordering, and the tendency for dopants to form clustered domains. In this work, we consider the defect thermodynamics and the dilute magnetic properties across charge states of 2D-MoS2 and 2D-WS2 with Mn magnetic dopants as candidate systems for 2D-DMSs. Using hybrid density functional calculations, we study the magnetic and electronic properties of these systems across configurations with thermodynamically favorable defects: 2D-MoS2 doped with Mn atoms at sulfur site (MnS), at two Mo sites (2MnMo), on top of a Mo atom (Mn-top), and at a Mo site (MnMo). While the majority of the Mn-defect complexes provide trap states, MnMo and MnW are amphoteric, although previously predicted to be donor defects. The impact of cluster formation of these amphoteric defects on magnetic ordering is also considered; both MnMo-MnMo (2Mn2Mo) and MnW-MnW (2Mn2W) clusters are found to be stable in ferromagnetic (FM) ordering. Interestingly, we observed the defect charge state dependent magnetic behavior of 2Mn2Mo and 2Mn2W clusters in 2D-TMDs. We investigate that the FM coupling of 2Mn2Mo and 2Mn2W clusters is stable in only a neutral charge state; however, the antiferromagnetic (AFM) coupling is stable in the +1 charge state. 2Mn2Mo clusters provide shallow donor levels in AFM coupling and deep donor levels in FM coupling. 2Mn2W clusters lead to trap states in the FM and AFM coupling. We demonstrate the AFM to FM phase transition at a critical electron density nce = 3.5 × 1013 cm-2 in 2D-MoS2 and 2D-WS2. At a 1.85% concentration of Mn, we calculate the Curie temperature of 580 K in the mean-field approximation.
Collapse
Affiliation(s)
- Akash Singh
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Christopher C Price
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Vivek B Shenoy
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| |
Collapse
|
33
|
Franklin GF, Balocchi A, Taberna PL, Barnabe A, Barbosa JB, Blei M, Tongay S, Marie X, Urita K, Chane-Ching JY. Mitigation of Edge and Surface States Effects in Two-Dimensional WS 2 for Photocatalytic H 2 Generation. CHEMSUSCHEM 2022; 15:e202200169. [PMID: 35230739 DOI: 10.1002/cssc.202200169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 03/01/2022] [Indexed: 06/14/2023]
Abstract
Large scale development of the 2D transition metal di-chalcogenides (TMDC) relies on landmark improvement in performance, which could emerge from nanostructuration. Using p-WS2 nanoflakes with different degrees of exfoliation and fracturing, perspectives were provided to develop high-surface-area 2D p-WS2 films for the photocatalytic hydrogen generation. The critical role of inter-nanoflakes contacts within high-surface-area 2D films was demonstrated, highlighting the benefit of plane/plane versus edge/plane contacts. Evidence of the high density of surface states displayed by these 2D films was provided through electrochemical measurements. In addition to operating as recombination centers, the surface states were shown to give rise to deleterious Fermi-level pinning (FLP), which dramatically decreased the efficiency of charge carrier separation. Lastly, promising strategies yielding FLP suppression via surface states modification were proposed. In particular, use of a multifunctional ultrathin film displaying healing, catalytic, and n-type semiconduction properties was shown to greatly enhance charge carrier separation and transport to the photo-electrode/electrolyte interface. When the 2D photoelectrodes were fabricated with the above prerequisites (i. e., a high proportion of plane/plane contacts and a successful surface states chemical modification), a photocurrent up to 4.5 mA cm-2 was achieved for the first time on 2D p-WS2 photocathodes for hydrogen generation.
Collapse
Affiliation(s)
| | - Andrea Balocchi
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Av. Rangueil, 31077, Toulouse, France
| | - Pierre-Louis Taberna
- UPS, CNRS, CIRIMAT, Université de Toulouse, 118 Route de Narbonne, F-31062, Toulouse, France
| | - Antoine Barnabe
- UPS, CNRS, CIRIMAT, Université de Toulouse, 118 Route de Narbonne, F-31062, Toulouse, France
| | - Juliana Barros Barbosa
- UPS, CNRS, CIRIMAT, Université de Toulouse, 118 Route de Narbonne, F-31062, Toulouse, France
| | - Mark Blei
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona, 85287, USA
| | - Sefaattin Tongay
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona, 85287, USA
| | - Xavier Marie
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Av. Rangueil, 31077, Toulouse, France
| | - Koki Urita
- Department of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan
| | - Jean Yves Chane-Ching
- UPS, CNRS, CIRIMAT, Université de Toulouse, 118 Route de Narbonne, F-31062, Toulouse, France
| |
Collapse
|
34
|
Liu X, Choi MS, Hwang E, Yoo WJ, Sun J. Fermi Level Pinning Dependent 2D Semiconductor Devices: Challenges and Prospects. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2108425. [PMID: 34913205 DOI: 10.1002/adma.202108425] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/29/2021] [Indexed: 06/14/2023]
Abstract
Motivated by the high expectation for efficient electrostatic modulation of charge transport at very low voltages, atomically thin 2D materials with a range of bandgaps are investigated extensively for use in future semiconductor devices. However, researchers face formidable challenges in 2D device processing mainly originated from the out-of-plane van der Waals (vdW) structure of ultrathin 2D materials. As major challenges, untunable Schottky barrier height and the corresponding strong Fermi level pinning (FLP) at metal interfaces are observed unexpectedly with 2D vdW materials, giving rise to unmodulated semiconductor polarity, high contact resistance, and lowered device mobility. Here, FLP observed from recently developed 2D semiconductor devices is addressed differently from those observed from conventional semiconductor devices. It is understood that the observed FLP is attributed to inefficient doping into 2D materials, vdW gap present at the metal interface, and hybridized compounds formed under contacting metals. To provide readers with practical guidelines for the design of 2D devices, the impact of FLP occurring in 2D semiconductor devices is further reviewed by exploring various origins responsible for the FLP, effects of FLP on 2D device performances, and methods for improving metallic contact to 2D materials.
Collapse
Affiliation(s)
- Xiaochi Liu
- School of Physics and Electronics, Central South University, Changsha, 410083, China
| | - Min Sup Choi
- SKKU Advanced Institute of Nano Technology, Sungkyunkwan University, Suwon, 16419, South Korea
| | - Euyheon Hwang
- SKKU Advanced Institute of Nano Technology, Sungkyunkwan University, Suwon, 16419, South Korea
| | - Won Jong Yoo
- SKKU Advanced Institute of Nano Technology, Sungkyunkwan University, Suwon, 16419, South Korea
| | - Jian Sun
- School of Physics and Electronics, Central South University, Changsha, 410083, China
| |
Collapse
|
35
|
V J, Mishra SS, Mb KU, Thomas SP, Tiwary CS, Biswas K, Kamble VB. Highly Sensitive and Selective Triethylamine Sensing through High-Entropy Alloy (Ti-Zr-Cr-V-Ni) Nanoparticle-Induced Fermi Energy Control of MoS 2 Nanosheets. ACS APPLIED MATERIALS & INTERFACES 2022; 14:13653-13664. [PMID: 35276048 DOI: 10.1021/acsami.2c00531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A giant enhancement of nearly 100 times is seen in triethylamine response through Ti-Zr-Cr-V-Ni high-entropy alloy nanoparticle (HEA NP)-induced fermi energy control of two-dimensional molybdenum disulfide (MoS2) nanosheets. These Laves-phase HEA NP-decorated MoS2 samples are synthesized using cryomilling followed by 30 h of sonication. The prolonged sonication results in well-exfoliated MoS2 with fairly small (∼10-20 nm) HEA NPs anchored due to cryomilling confirmed by extensive microscopic and spectroscopic examinations. The presence of HEA NPs leads to reduction in edge oxidation of MoS2 as seen from X-ray photoelectron spectroscopy. Moreover, this edge state reduction causes strong Fermi level pinning, which is commonly observed in layered MoS2 with bulk metal electrodes. This leads to target gas-specific carrier-type response and selective oxidation of TEA vapors due to highly catalytically active metals. The resulting composite (MoS2 + NPs) exhibits high response (380% for 2000 ppm TEA vapors) along with selectivity toward TEA at 50 °C. The cross-sensitivity of the composite to other volatile organic compounds and NH3, CO, and H2 has been very minimal. Thus, the highly selective catalytic activity of metal alloy NPs and their Fermi energy control has been proposed as the prime factors for observed large sensitivity and selective response of MoS2 + NP nanocomposites.
Collapse
Affiliation(s)
- Jishnu V
- School of Physics, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| | - Shashank Shekhar Mishra
- Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Kusuma Urs Mb
- School of Physics, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| | - Sanchu P Thomas
- School of Physics, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| | - Chandra Sekhar Tiwary
- Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, Kharagpur 382355, India
| | - Krishanu Biswas
- Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Vinayak B Kamble
- School of Physics, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| |
Collapse
|
36
|
Ciampalini G, Fabbri F, Menichetti G, Buoni L, Pace S, Mišeikis V, Pitanti A, Pisignano D, Coletti C, Tredicucci A, Roddaro S. Unexpected Electron Transport Suppression in a Heterostructured Graphene-MoS 2 Multiple Field-Effect Transistor Architecture. ACS NANO 2022; 16:1291-1300. [PMID: 34939407 PMCID: PMC8793137 DOI: 10.1021/acsnano.1c09131] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 12/17/2021] [Indexed: 06/14/2023]
Abstract
We demonstrate a graphene-MoS2 architecture integrating multiple field-effect transistors (FETs), and we independently probe and correlate the conducting properties of van der Waals coupled graphene-MoS2 contacts with those of the MoS2 channels. Devices are fabricated starting from high-quality single-crystal monolayers grown by chemical vapor deposition. The heterojunction was investigated by scanning Raman and photoluminescence spectroscopies. Moreover, transconductance curves of MoS2 are compared with the current-voltage characteristics of graphene contact stripes, revealing a significant suppression of transport on the n-side of the transconductance curve. On the basis of ab initio modeling, the effect is understood in terms of trapping by sulfur vacancies, which counterintuitively depends on the field effect, even though the graphene contact layer is positioned between the backgate and the MoS2 channel.
Collapse
Affiliation(s)
- Gaia Ciampalini
- Dipartimento
di Fisica “E. Fermi”, Università
di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
- Graphene
Labs, Istituto Italiano di Tecnologia, Via Morego 30, I-16 163 Genova, Italy
- NEST,
CNR—Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, I-56 127 Pisa, Italy
| | - Filippo Fabbri
- NEST,
CNR—Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, I-56 127 Pisa, Italy
| | - Guido Menichetti
- Dipartimento
di Fisica “E. Fermi”, Università
di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
- Graphene
Labs, Istituto Italiano di Tecnologia, Via Morego 30, I-16 163 Genova, Italy
| | - Luca Buoni
- Dipartimento
di Fisica “E. Fermi”, Università
di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
| | - Simona Pace
- Graphene
Labs, Istituto Italiano di Tecnologia, Via Morego 30, I-16 163 Genova, Italy
- Center
for Nanotechnology Innovation @NEST, Istituto
Italiano di Tecnologia, Piazza San Silvestro 12, I-56 127 Pisa, Italy
| | - Vaidotas Mišeikis
- Graphene
Labs, Istituto Italiano di Tecnologia, Via Morego 30, I-16 163 Genova, Italy
- Center
for Nanotechnology Innovation @NEST, Istituto
Italiano di Tecnologia, Piazza San Silvestro 12, I-56 127 Pisa, Italy
| | - Alessandro Pitanti
- NEST,
CNR—Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, I-56 127 Pisa, Italy
| | - Dario Pisignano
- Dipartimento
di Fisica “E. Fermi”, Università
di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
- NEST,
CNR—Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, I-56 127 Pisa, Italy
| | - Camilla Coletti
- Graphene
Labs, Istituto Italiano di Tecnologia, Via Morego 30, I-16 163 Genova, Italy
- Center
for Nanotechnology Innovation @NEST, Istituto
Italiano di Tecnologia, Piazza San Silvestro 12, I-56 127 Pisa, Italy
| | - Alessandro Tredicucci
- Dipartimento
di Fisica “E. Fermi”, Università
di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
- NEST,
CNR—Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, I-56 127 Pisa, Italy
| | - Stefano Roddaro
- Dipartimento
di Fisica “E. Fermi”, Università
di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
- NEST,
CNR—Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, I-56 127 Pisa, Italy
| |
Collapse
|
37
|
Panasci SE, Koos A, Schilirò E, Di Franco S, Greco G, Fiorenza P, Roccaforte F, Agnello S, Cannas M, Gelardi FM, Sulyok A, Nemeth M, Pécz B, Giannazzo F. Multiscale Investigation of the Structural, Electrical and Photoluminescence Properties of MoS 2 Obtained by MoO 3 Sulfurization. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:182. [PMID: 35055201 PMCID: PMC8778062 DOI: 10.3390/nano12020182] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/01/2022] [Accepted: 01/03/2022] [Indexed: 01/27/2023]
Abstract
In this paper, we report a multiscale investigation of the compositional, morphological, structural, electrical, and optical emission properties of 2H-MoS2 obtained by sulfurization at 800 °C of very thin MoO3 films (with thickness ranging from ~2.8 nm to ~4.2 nm) on a SiO2/Si substrate. XPS analyses confirmed that the sulfurization was very effective in the reduction of the oxide to MoS2, with only a small percentage of residual MoO3 present in the final film. High-resolution TEM/STEM analyses revealed the formation of few (i.e., 2-3 layers) of MoS2 nearly aligned with the SiO2 surface in the case of the thinnest (~2.8 nm) MoO3 film, whereas multilayers of MoS2 partially standing up with respect to the substrate were observed for the ~4.2 nm one. Such different configurations indicate the prevalence of different mechanisms (i.e., vapour-solid surface reaction or S diffusion within the film) as a function of the thickness. The uniform thickness distribution of the few-layer and multilayer MoS2 was confirmed by Raman mapping. Furthermore, the correlative plot of the characteristic A1g-E2g Raman modes revealed a compressive strain (ε ≈ -0.78 ± 0.18%) and the coexistence of n- and p-type doped areas in the few-layer MoS2 on SiO2, where the p-type doping is probably due to the presence of residual MoO3. Nanoscale resolution current mapping by C-AFM showed local inhomogeneities in the conductivity of the few-layer MoS2, which are well correlated to the lateral changes in the strain detected by Raman. Finally, characteristic spectroscopic signatures of the defects/disorder in MoS2 films produced by sulfurization were identified by a comparative analysis of Raman and photoluminescence (PL) spectra with CVD grown MoS2 flakes.
Collapse
Affiliation(s)
- Salvatore E. Panasci
- Consiglio Nazionale delle Ricerche—Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII 5, 95121 Catania, Italy; (S.E.P.); (E.S.); (S.D.F.); (G.G.); (P.F.); (F.R.); (S.A.)
- Department of Physics and Astronomy, University of Catania, 95123 Catania, Italy
| | - Antal Koos
- Centre for Energy Research, Institute of Technical Physics and Materials Science, Konkoly-Thege ut 29-33, 1121 Budapest, Hungary; (A.K.); (A.S.); (M.N.)
| | - Emanuela Schilirò
- Consiglio Nazionale delle Ricerche—Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII 5, 95121 Catania, Italy; (S.E.P.); (E.S.); (S.D.F.); (G.G.); (P.F.); (F.R.); (S.A.)
| | - Salvatore Di Franco
- Consiglio Nazionale delle Ricerche—Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII 5, 95121 Catania, Italy; (S.E.P.); (E.S.); (S.D.F.); (G.G.); (P.F.); (F.R.); (S.A.)
| | - Giuseppe Greco
- Consiglio Nazionale delle Ricerche—Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII 5, 95121 Catania, Italy; (S.E.P.); (E.S.); (S.D.F.); (G.G.); (P.F.); (F.R.); (S.A.)
| | - Patrick Fiorenza
- Consiglio Nazionale delle Ricerche—Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII 5, 95121 Catania, Italy; (S.E.P.); (E.S.); (S.D.F.); (G.G.); (P.F.); (F.R.); (S.A.)
| | - Fabrizio Roccaforte
- Consiglio Nazionale delle Ricerche—Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII 5, 95121 Catania, Italy; (S.E.P.); (E.S.); (S.D.F.); (G.G.); (P.F.); (F.R.); (S.A.)
| | - Simonpietro Agnello
- Consiglio Nazionale delle Ricerche—Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII 5, 95121 Catania, Italy; (S.E.P.); (E.S.); (S.D.F.); (G.G.); (P.F.); (F.R.); (S.A.)
- Department of Physics and Chemistry Emilio Segrè, University of Palermo, 90123 Palermo, Italy; (M.C.); (F.M.G.)
- ATEN Center, University of Palermo, 90123 Palermo, Italy
| | - Marco Cannas
- Department of Physics and Chemistry Emilio Segrè, University of Palermo, 90123 Palermo, Italy; (M.C.); (F.M.G.)
| | - Franco M. Gelardi
- Department of Physics and Chemistry Emilio Segrè, University of Palermo, 90123 Palermo, Italy; (M.C.); (F.M.G.)
| | - Attila Sulyok
- Centre for Energy Research, Institute of Technical Physics and Materials Science, Konkoly-Thege ut 29-33, 1121 Budapest, Hungary; (A.K.); (A.S.); (M.N.)
| | - Miklos Nemeth
- Centre for Energy Research, Institute of Technical Physics and Materials Science, Konkoly-Thege ut 29-33, 1121 Budapest, Hungary; (A.K.); (A.S.); (M.N.)
| | - Béla Pécz
- Centre for Energy Research, Institute of Technical Physics and Materials Science, Konkoly-Thege ut 29-33, 1121 Budapest, Hungary; (A.K.); (A.S.); (M.N.)
| | - Filippo Giannazzo
- Consiglio Nazionale delle Ricerche—Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII 5, 95121 Catania, Italy; (S.E.P.); (E.S.); (S.D.F.); (G.G.); (P.F.); (F.R.); (S.A.)
| |
Collapse
|
38
|
Recent Progress in Two-Dimensional MoTe 2 Hetero-Phase Homojunctions. NANOMATERIALS 2021; 12:nano12010110. [PMID: 35010060 PMCID: PMC8746702 DOI: 10.3390/nano12010110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/21/2021] [Accepted: 12/27/2021] [Indexed: 11/17/2022]
Abstract
With the demand for low contact resistance and a clean interface in high-performance field-effect transistors, two-dimensional (2D) hetero-phase homojunctions, which comprise a semiconducting phase of a material as the channel and a metallic phase of the material as electrodes, have attracted growing attention in recent years. In particular, MoTe2 exhibits intriguing properties and its phase is easily altered from semiconducting 2H to metallic 1T' and vice versa, owing to the extremely small energy barrier between these two phases. MoTe2 thus finds potential applications in electronics as a representative 2D material with multiple phases. In this review, we briefly summarize recent progress in 2D MoTe2 hetero-phase homojunctions. We first introduce the properties of the diverse phases of MoTe2, demonstrate the approaches to the construction of 2D MoTe2 hetero-phase homojunctions, and then show the applications of the homojunctions. Lastly, we discuss the prospects and challenges in this research field.
Collapse
|
39
|
Ni J, Fu Q, Ostrikov KK, Gu X, Nan H, Xiao S. Status and prospects of Ohmic contacts on two-dimensional semiconductors. NANOTECHNOLOGY 2021; 33:062005. [PMID: 34649226 DOI: 10.1088/1361-6528/ac2fe1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Accepted: 10/14/2021] [Indexed: 06/13/2023]
Abstract
In recent years, two-dimensional materials have received more and more attention in the development of semiconductor devices, and their practical applications in optoelectronic devices have also developed rapidly. However, there are still some factors that limit the performance of two-dimensional semiconductor material devices, and one of the most important is Ohmic contact. Here, we elaborate on a variety of approaches to achieve Ohmic contacts on two-dimensional materials and reveal their physical mechanisms. For the work function mismatch problem, we summarize the comparison of barrier heights between different metals and 2D semiconductors. We also examine different methods to solve the problem of Fermi level pinning. For the novel 2D metal-semiconductor contact methods, we analyse their effects on reducing contact resistance from two different perspectives: homojunction and heterojunction. Finally, the challenges of 2D semiconductors in achieving Ohmic contacts are outlined.
Collapse
Affiliation(s)
- Junhao Ni
- Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Quangui Fu
- Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Kostya Ken Ostrikov
- School of Chemistry and Physics and QUT Centre for Materials Science, Queensland University of Technology (QUT), Brisbane QLD 4000, Australia
| | - Xiaofeng Gu
- Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Haiyan Nan
- Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Shaoqing Xiao
- Engineering Research Center of IoT Technology Applications (Ministry of Education), Department of Electronic Engineering, Jiangnan University, Wuxi 214122, People's Republic of China
| |
Collapse
|
40
|
Helal MA, El-Sayed HM, Maarouf AA, Fadlallah MM. Metal dichalcogenide nanomeshes: structural, electronic and magnetic properties. Phys Chem Chem Phys 2021; 23:21183-21195. [PMID: 34528957 DOI: 10.1039/d1cp03743a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Motivated by the successful preparation of two-dimensional transition metal dichalcogenide (2D-TMD) nanomeshes in the last three years, we use density functional theory (DFT) to study the structural stability, mechanical, magnetic, and electronic properties of porous 2H-MoX2 (X = S, Se and Te) without and with pore passivation. We consider structures with multiple, systematically created pores. The molecular dynamics simulations and cohesive energy calculations showed the stability of the 2D-TMD nanomeshes, with larger stability for those with smaller pores. The lattice undergoes some deformations to accommodate the pore energetically, and as the pore size increases Young's modulus decreases. In most cases, the missing metal atoms disrupt the spin states' even population, resulting in some nanomeshes becoming magnetic. The electronic gaps of the MoX2 nanomesh systems are diminished because of the emergence of pore-edge localized mid-gap metal 4d states in the spin-polarized spectrum, making some systems half-metallic. The oxygen passivation of the pore edges of 2D-TMD nanomeshes restores the even population of spin states, and makes those systems metallic. Our results can be used in different applications such as spintronics, ion chelation, and molecular sensing applications.
Collapse
Affiliation(s)
- Mohamed A Helal
- Department of Physics, Faculty of Science, Ain Shams University, Cairo 11566, Egypt
| | - H M El-Sayed
- Department of Physics, Faculty of Science, Ain Shams University, Cairo 11566, Egypt
| | - Ahmed A Maarouf
- Department of Physics, Institute for Research and Medical Consultations, Imam Abdulrahman Bin Faisal University, Dammam 31441, Saudi Arabia.
| | - Mohamed M Fadlallah
- Department of Physics, Faculty of Science, Benha University, Benha 13518, Egypt.
| |
Collapse
|
41
|
Pang CS, Zhou R, Liu X, Wu P, Hung TYT, Guo S, Zaghloul ME, Krylyuk S, Davydov AV, Appenzeller J, Chen Z. Mobility Extraction in 2D Transition Metal Dichalcogenide Devices-Avoiding Contact Resistance Implicated Overestimation. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2100940. [PMID: 34110675 PMCID: PMC9703574 DOI: 10.1002/smll.202100940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/25/2021] [Indexed: 06/01/2023]
Abstract
Schottky barrier (SB) transistors operate distinctly different from conventional metal-oxide semiconductor field-effect transistors, in a unique way that the gate impacts the carrier injection from the metal source/drain contacts into the channel region. While it has been long recognized that this can have severe implications for device characteristics in the subthreshold region, impacts of contact gating of SB in the on-state of the devices, which affects evaluation of intrinsic channel properties, have been yet comprehensively studied. Due to the fact that contact resistance (RC ) is always gate-dependent in a typical back-gated device structure, the traditional approach of deriving field-effect mobility from the maximum transconductance (gm ) is in principle not correct and can even overestimate the mobility. In addition, an exhibition of two different threshold voltages for the channel and the contact region leads to another layer of complexity in determining the true carrier concentration calculated from Q = COX * (VG -VTH ). Through a detailed experimental analysis, the effect of different effective oxide thicknesses, distinct SB heights, and doping-induced reductions in the SB width are carefully evaluated to gain a better understanding of their impact on important device metrics.
Collapse
Affiliation(s)
- Chin-Sheng Pang
- Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, 1205 W State St, West Lafayette, IN, 47907, USA
| | - Ruiping Zhou
- Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, 1205 W State St, West Lafayette, IN, 47907, USA
| | - Xiangkai Liu
- Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, 1205 W State St, West Lafayette, IN, 47907, USA
| | - Peng Wu
- Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, 1205 W State St, West Lafayette, IN, 47907, USA
| | - Terry Y T Hung
- Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, 1205 W State St, West Lafayette, IN, 47907, USA
| | - Shiqi Guo
- School of Engineering and Applied Science, The George Washington University, Washington, DC, 20052, USA
| | - Mona E Zaghloul
- School of Engineering and Applied Science, The George Washington University, Washington, DC, 20052, USA
| | - Sergiy Krylyuk
- Materials Science and Engineering Division, National Institute of Standards and Technology (NIST), Gaithersburg, MD, 20899, USA
| | - Albert V Davydov
- Materials Science and Engineering Division, National Institute of Standards and Technology (NIST), Gaithersburg, MD, 20899, USA
| | - Joerg Appenzeller
- Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, 1205 W State St, West Lafayette, IN, 47907, USA
| | - Zhihong Chen
- Birck Nanotechnology Center, Department of Electrical and Computer Engineering, Purdue University, 1205 W State St, West Lafayette, IN, 47907, USA
| |
Collapse
|
42
|
Kim S, Shin DH, Kim YS, Lee IH, Lee CW, Seo S, Jung S. Highly Efficient Experimental Approach to Evaluate Metal to 2D Semiconductor Interfaces in Vertical Diodes with Asymmetric Metal Contacts. ACS APPLIED MATERIALS & INTERFACES 2021; 13:27705-27712. [PMID: 34082527 DOI: 10.1021/acsami.1c07905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The energy band alignments and associated material properties at the contacts between metal and two-dimensional (2D) semiconducting transition metal dichalcogenide (SCTMD) films determine the important traits in 2D SCTMD-based electronic and optical device applications. In this work, we realize 2D vertical diodes with asymmetric metal-SCTMD contact areas where currents are dominated by the contact-limited charge flows in the transport regimes of Fowler-Nordheim tunneling and Schottky emission. With straightforward current-voltage characteristics, we can accurately evaluate the interface parameters such as Schottky barrier heights and the vertical effective masses of tunneling charges. In particular, the differing contact areas and resultant current rectifications allow us to address specific Schottky barrier locations with respect to the conduction and valence band edges of 2D semiconducting WSe2, WS2, MoSe2, and MoS2, thereby determining whether p-type holes or n-type electrons become the majority charge carriers in the SCTMD devices. We demonstrate that our experimental and analytical approaches can be utilized as a simple but powerful material metrology to qualitatively and quantitatively evaluate various metal-SCTMD contacts.
Collapse
Affiliation(s)
- Seonyeong Kim
- Interdisciplinary Materials Measurement Institute, Korea Research Institute of Standards and Science, Daejeon 34113, Korea (Republic of)
- Department of Physics, Sejong University, Seoul 05006, Korea (Republic of)
| | - Dong Hoon Shin
- Department of Physics, Ewha Womans University, Seoul 03760, Korea (Republic of)
| | - Yong-Sung Kim
- Interdisciplinary Materials Measurement Institute, Korea Research Institute of Standards and Science, Daejeon 34113, Korea (Republic of)
| | - In Ho Lee
- Interdisciplinary Materials Measurement Institute, Korea Research Institute of Standards and Science, Daejeon 34113, Korea (Republic of)
| | - Chang-Won Lee
- Department of Applied Optics, Institute of Advanced Optics and Photonics, Hanbat National University, Daejeon, 34158, Korea (Republic of)
| | - Sunae Seo
- Department of Physics, Sejong University, Seoul 05006, Korea (Republic of)
| | - Suyong Jung
- Interdisciplinary Materials Measurement Institute, Korea Research Institute of Standards and Science, Daejeon 34113, Korea (Republic of)
| |
Collapse
|
43
|
Ultralow contact resistance between semimetal and monolayer semiconductors. Nature 2021; 593:211-217. [PMID: 33981050 DOI: 10.1038/s41586-021-03472-9] [Citation(s) in RCA: 287] [Impact Index Per Article: 95.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 03/18/2021] [Indexed: 11/08/2022]
Abstract
Advanced beyond-silicon electronic technology requires both channel materials and also ultralow-resistance contacts to be discovered1,2. Atomically thin two-dimensional semiconductors have great potential for realizing high-performance electronic devices1,3. However, owing to metal-induced gap states (MIGS)4-7, energy barriers at the metal-semiconductor interface-which fundamentally lead to high contact resistance and poor current-delivery capability-have constrained the improvement of two-dimensional semiconductor transistors so far2,8,9. Here we report ohmic contact between semimetallic bismuth and semiconducting monolayer transition metal dichalcogenides (TMDs) where the MIGS are sufficiently suppressed and degenerate states in the TMD are spontaneously formed in contact with bismuth. Through this approach, we achieve zero Schottky barrier height, a contact resistance of 123 ohm micrometres and an on-state current density of 1,135 microamps per micrometre on monolayer MoS2; these two values are, to the best of our knowledge, the lowest and highest yet recorded, respectively. We also demonstrate that excellent ohmic contacts can be formed on various monolayer semiconductors, including MoS2, WS2 and WSe2. Our reported contact resistances are a substantial improvement for two-dimensional semiconductors, and approach the quantum limit. This technology unveils the potential of high-performance monolayer transistors that are on par with state-of-the-art three-dimensional semiconductors, enabling further device downscaling and extending Moore's law.
Collapse
|
44
|
Le Thi HY, Khan MA, Venkatesan A, Watanabe K, Taniguchi T, Kim GH. High-performance ambipolar MoS 2transistor enabled by indium edge contacts. NANOTECHNOLOGY 2021; 32:215701. [PMID: 33556924 DOI: 10.1088/1361-6528/abe438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 02/08/2021] [Indexed: 06/12/2023]
Abstract
The integration of electrical contact into 2D heterostructure is an essential approach to high-quality electronic nano-devices, especially field-effect transistors. However, high contact resistance with transition metal dichalcogenides such as molybdenum disulphide (MoS2)-based devices has been a significant fabrication impediment to their potential applications. Here, we have demonstrated the advantage of 1D indium metal contact with fully encapsulated MoS2within hexagonal boron nitride. The electrical measurements of the device exhibit ambipolar transport with an on/off ratio of102for holes and107for electrons. The device exhibits high field-effect mobility of40.7cm2V-1s-1at liquid nitrogen temperature. Furthermore, we have also analysed the charge-transport mechanism at the interface and have calculated the Schottky barrier height from the temperature-dependent measurement. These results are highly promising for the use of air-sensitive material heterostructure and large-scale design of trending flexible, transparent electronic wearable devices.
Collapse
Affiliation(s)
- Hai Yen Le Thi
- Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Muhammad Atif Khan
- Department of Electrical and Computer Engineering, Air University, Sector E-9, Islamabad, Pakistan
| | - A Venkatesan
- School of Electronic and Electrical Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Material Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Gil-Ho Kim
- Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
- School of Electronic and Electrical Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| |
Collapse
|
45
|
Bussolotti F, Yang J, Kawai H, Wong CPY, Goh KEJ. Impact of S-Vacancies on the Charge Injection Barrier at the Electrical Contact with the MoS 2 Monolayer. ACS NANO 2021; 15:2686-2697. [PMID: 33502172 DOI: 10.1021/acsnano.0c07982] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Making electrical contacts to semiconducting transition metal dichalcogenides (TMDCs) represents a major bottleneck for high device performance, often manifesting as strong Fermi level pinning and high contact resistance. Despite intense ongoing research, the mechanism by which lattice defects in TMDCs impact the transport properties across the contact-TMDC interface remains unsettled. Here we study the impact of S-vacancies on the electronic properties at a MoS2 monolayer interfaced with graphite by photoemission spectroscopy, where the defect density is selectively controlled by Ar sputtering. A clear reduction of the MoS2 core level and valence band binding energies is observed as the defect density increases. The experimental results are explained in terms of (i) gap states' energy distribution and (ii) S-vacancies' electrostatic disorder effect. Our model indicates that the Fermi level pinning at deep S-vacancy gap states is the origin of the commonly reported large electron injection barrier (∼0.5 eV) at the MoS2 ML interface with low work function metals. At the contact with high work function electrodes, S-vacancies do not significantly affect the hole injection barrier, which is intrinsically favored by Fermi level pinning at shallow occupied gap states. Our results clarify the importance of S-vacancies and electrostatic disorder in TMDC-based electronic devices, which could lead to strategies for optimizing device performance and production.
Collapse
Affiliation(s)
- Fabio Bussolotti
- Institute of Materials Research & Engineering (IMRE), Agency for Science, Technology, and Research (A*STAR), 2 Fusionopolis Way, #08-03 Innovis, Singapore 138634, Singapore
| | - Jing Yang
- Institute of High Performance Computing (IHPC), Agency for Science, Technology and Research (A*STAR), 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore
| | - Hiroyo Kawai
- Institute of High Performance Computing (IHPC), Agency for Science, Technology and Research (A*STAR), 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore
| | - Calvin Pei Yu Wong
- Institute of Materials Research & Engineering (IMRE), Agency for Science, Technology, and Research (A*STAR), 2 Fusionopolis Way, #08-03 Innovis, Singapore 138634, Singapore
| | - Kuan Eng Johnson Goh
- Institute of Materials Research & Engineering (IMRE), Agency for Science, Technology, and Research (A*STAR), 2 Fusionopolis Way, #08-03 Innovis, Singapore 138634, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| |
Collapse
|
46
|
Lim J, Kadyrov A, Jeon D, Choi Y, Bae J, Lee S. Contact Engineering of Vertically Grown ReS 2 with Schottky Barrier Modulation. ACS APPLIED MATERIALS & INTERFACES 2021; 13:7529-7538. [PMID: 33544572 DOI: 10.1021/acsami.0c20108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Forming metal contact with low contact resistance is essential for the development of electronics based on layered van der Waals materials. ReS2 is a semiconducting transition metal dichalcogenide (TMD) with an MX2 structure similar to that of MoS2. While most TMDs grow parallel to the substrate when synthesized using chemical vapor deposition (CVD), ReS2 tends to orient itself vertically during growth. Such a feature drastically increases the surface area and exposes chemically active edges, making ReS2 an attractive layered material for energy and sensor applications. However, the contact resistances of vertically grown materials are known to be relatively high, compared to those of common 2H-phase TMDs, such as MoS2. Most reported methods for lowering the contact resistance have been focused on exfoliated 2H-phase materials with only a few devices tested, and few works on distorted T-phase materials exist. Moreover, nearly all reported studies have been conducted on only a few devices with mechanically exfoliated fl Most reported methods for lowering the contact resistance have been 2 contacts was modulated by conformally coating a thin tunneling interlayer between the metal and the dendritic ReS2 film. Over a hundred devices were tested, and contact resistances were extracted for large-scale statistical analysis. Importantly, we compared various known materials and techniques for lowering contact resistance and found an optimized method. Finally, the reductions in barrier height were directly correlated with exponential reductions in contact resistance and increases in drive-current by almost 2 orders of magnitude.
Collapse
Affiliation(s)
- Jinho Lim
- Semiconductor Device & Integration Laboratory, Department of Electronic Engineering, Kyunghee University, Yongin 17104, Korea
| | - Arman Kadyrov
- Semiconductor Device & Integration Laboratory, Department of Electronic Engineering, Kyunghee University, Yongin 17104, Korea
| | - Dasom Jeon
- Semiconductor Device & Integration Laboratory, Department of Electronic Engineering, Kyunghee University, Yongin 17104, Korea
| | - Yongsu Choi
- Semiconductor Device & Integration Laboratory, Department of Electronic Engineering, Kyunghee University, Yongin 17104, Korea
| | - Junho Bae
- Semiconductor Device & Integration Laboratory, Department of Electronic Engineering, Kyunghee University, Yongin 17104, Korea
| | - Seunghyun Lee
- Semiconductor Device & Integration Laboratory, Department of Electronic Engineering, Kyunghee University, Yongin 17104, Korea
| |
Collapse
|
47
|
Khan MF, Ahmed F, Rehman S, Akhtar I, Rehman MA, Shinde PA, Khan K, Kim DK, Eom J, Lipsanen H, Sun Z. High performance complementary WS 2 devices with hybrid Gr/Ni contacts. NANOSCALE 2020; 12:21280-21290. [PMID: 33063794 DOI: 10.1039/d0nr05737a] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Two-dimensional (2D) transition metal dichalcogenides have attracted vibrant interest for future solid-state device applications due to their unique properties. However, it is challenging to realize 2D material based high performance complementary devices due to the stubborn Fermi level pinning effect and the lack of facile doping techniques. In this paper, we reported a hybrid Gr/Ni contact to WS2, which can switch carrier types from n-type to p-type in WS2. The unorthodox polarity transition is attributed to the natural p-doping of graphene with Ni adsorption and the alleviation of Fermi level pinning in WS2. Furthermore, we realized asymmetric Ni and Gr/Ni hybrid contacts to a multilayer WS2 device, and we observed synergistic p-n diode characteristics with excellent current rectification exceeding 104, and a near unity ideality factor of 1.1 (1.6) at a temperature of 4.5 K (300 K). Lastly, our WS2 p-n device exhibits high performance photovoltaic ability with a maximum photoresponsivity of 4 × 104 A W-1 at 532 nm wavelength, that is 108 times higher than that of graphene and 50 times better than that of the monolayer MoS2 photodetector. This doping-free carrier type modulation technique will pave the way to realize high performance complementary electronics and optoelectronic devices based on 2D materials.
Collapse
Affiliation(s)
- Muhammad Farooq Khan
- Department of Electrical Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Korea.
| | - Faisal Ahmed
- Department of Electronics and Nanoengineering, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland and Department of Mechanical Engineering, College of Electrical and Mechanical Engineering, National University of Science and Technology, Islamabad 44000, Pakistan
| | - Shania Rehman
- Department of Electrical Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Korea.
| | - Imtisal Akhtar
- Department of Mechanical Engineering, Chung-Ang University, Seoul, South Korea
| | - Malik Abdul Rehman
- School of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea
| | - Pragati A Shinde
- School of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea
| | - Karim Khan
- School of Electrical Engineering & Intelligentization, Dongguan University of Technology (DGUT), Dongguan, 523808, Guangdong, China and Institute of Microscale Optoelectronics, Collaborative Innovation Centre for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen Key Laboratory of Micro-Nano Photonic Information Technology, Guangdong Laboratory of Artificial Intelligence and Digital Economy (SZ), Shenzhen University, Shenzhen 518060, P.R. China
| | - Deok-Kee Kim
- Department of Electrical Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Korea.
| | - Jonghwa Eom
- Graphene Research Institute-Texas Photonics Center International Research Center (GRI-TPCIRC), Sejong University, Seoul 05006, Korea
| | - Harri Lipsanen
- Department of Electronics and Nanoengineering, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Zhipei Sun
- Department of Electronics and Nanoengineering, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland and QTF Centre of Excellence, Department of Applied Physics, Aalto University, Aalto 00076, Finland
| |
Collapse
|
48
|
Sun H, Zhou X, Wang X, Xu L, Zhang J, Jiang K, Shang L, Hu Z, Chu J. P-N conversion of charge carrier types and high photoresponsive performance of composition modulated ternary alloy W(S xSe 1-x) 2 field-effect transistors. NANOSCALE 2020; 12:15304-15317. [PMID: 32648866 DOI: 10.1039/d0nr04633g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Transition metal dichalcogenides (TMDs) have emerged as a new class of two-dimensional (2D) materials, which are promising for diverse applications in nanoelectronics, optoelectronics, and photonics. To satisfy the requirements of the building blocks of functional devices, systematic modulation of the band gap and carrier type of TMDs materials becomes a significant challenge. Here, we report a salt-assisted chemical vapor deposition (CVD) approach for the simultaneous growth of alloy W(SxSe1-x)2 nanosheets with variable alloy compositions. Electrical transport studies based on the as-fabricated W(SxSe1-x)2 nanosheet field-effect transistors (FETs) demonstrate that charge carrier types of alloy nanosheet transistors can be systematically tuned by adjusting the alloy composition. Temperature-dependent current measurement shows that the main scattering mechanism is the charged impurity scattering. The effective Schottky barrier heights of bipolar W(SxSe1-x)2 transistors are initially increased and then decreased with increasing positive (or negative) gate voltage, which is tunable by varying the alloy composition. In addition, the tunability of these W(SxSe1-x)2-based ambipolar transistors is suitable for logic and analog applications and represents a critical step toward future fundamental studies as well as for the rational design of new 2D electronics with tailored spectral responses, and simpler and higher integration densities. Finally, the high photoresponsivity (up to 914 mA W-1) and detectivity (4.57 × 1010 Jones) of ultrathin W(SxSe1-x)2 phototransistors imply their potential applications in flexible light-detection and light-harvesting devices. These band gap engineered 2D structures could open up an exciting opportunity and contribute to finding diverse applications in future functional electronic/optoelectronic devices.
Collapse
Affiliation(s)
- Huimin Sun
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China.
| | - Xin Zhou
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China.
| | - Xiang Wang
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China.
| | - Liping Xu
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China.
| | - Jinzhong Zhang
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China.
| | - Kai Jiang
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China.
| | - Liyan Shang
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China.
| | - Zhigao Hu
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China. and Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China and Shanghai Institute of Intelligent Electronics & Systems, Fudan University, Shanghai 200433, China
| | - Junhao Chu
- Technical Center for Multifunctional Magneto-Optical Spectroscopy (Shanghai), Engineering Research Center of Nanophotonics & Advanced Instrument (Ministry of Education), Department of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China. and Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China and Shanghai Institute of Intelligent Electronics & Systems, Fudan University, Shanghai 200433, China
| |
Collapse
|
49
|
Yan W, Lv C, Zhang D, Chen Y, Zhang L, Ó Coileáin C, Wang Z, Jiang Z, Hung KM, Chang CR, Wu HC. Enhanced NO 2 Sensitivity in Schottky-Contacted n-Type SnS 2 Gas Sensors. ACS APPLIED MATERIALS & INTERFACES 2020; 12:26746-26754. [PMID: 32426961 DOI: 10.1021/acsami.0c07193] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Layered materials are highly attractive in gas sensor research due to their extraordinary electronic and physicochemical properties. The development of cheaper and faster room-temperature detectors with high sensitivities especially in the parts per billion level is the main challenge in this rapidly developing field. Here, we show that sensitivity to NO2 (S) can be greatly improved by at least two orders of magnitude using an n-type electrode metal. Unconventionally for such devices, the ln(S) follows the classic Langmuir isotherm model rather than S as is for a p-type electrode metal. Excellent device sensitivities, as high as 13,000% for 9 ppm and 97% for 1 ppb NO2, are achieved with Mn electrodes at room temperature, which can be further tuned and enhanced with the application of a bias. Long-term stability, fast recovery, and strong selectivity toward NO2 are also demonstrated. Such impressive features provide a real solution for designing a practical high-performance layered material-based gas sensor.
Collapse
Affiliation(s)
- Wenjie Yan
- School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Chengzhai Lv
- School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Duan Zhang
- Elementary Educational College, Beijing key Laboratory for Nano-Photonics and Nano-Structure, Capital Normal University, Beijing 100048, P. R. China
| | - Yanhui Chen
- Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing, 100124, China
| | - Lei Zhang
- Foshan (Southern China) Institute for New Materials, Guangdong 528000, China
| | - Cormac Ó Coileáin
- CRANN and AMBER, School of Chemistry, Trinity College, Dublin Dublin 2, Ireland
| | - Zhi Wang
- School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Zhaotan Jiang
- School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China
| | - Kuan-Ming Hung
- Department of Electronics Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 807, Taiwan, ROC
| | - Ching-Ray Chang
- Department of Physics, National Taiwan University, Taipei 106, Taiwan
| | - Han-Chun Wu
- School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China
| |
Collapse
|
50
|
Liao W, Zhao S, Li F, Wang C, Ge Y, Wang H, Wang S, Zhang H. Interface engineering of two-dimensional transition metal dichalcogenides towards next-generation electronic devices: recent advances and challenges. NANOSCALE HORIZONS 2020; 5:787-807. [PMID: 32129353 DOI: 10.1039/c9nh00743a] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Over the past decade, two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted tremendous research interest for future electronics owing to their atomically thin thickness, compelling properties and various potential applications. However, interface engineering including contact optimization and channel modulations for 2D TMDCs represents fundamental challenges in ultimate performance of ultrathin electronics. This article provides a comprehensive overview of the basic understanding of contacts and channel engineering of 2D TMDCs and emerging electronics benefiting from these varying approaches. In particular, we elucidate multifarious contact engineering approaches such as edge contact, phase engineering and metal transfer to suppress the Fermi level pinning effect at the metal/TMDC interface, various channel treatment avenues such as van der Waals heterostructures, surface charge transfer doping to modulate the device properties, and as well the novel electronics constructed by interface engineering such as diodes, circuits and memories. Finally, we conclude this review by addressing the current challenges facing 2D TMDCs towards next-generation electronics and offering our insights into future directions of this field.
Collapse
Affiliation(s)
- Wugang Liao
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China.
| | | | | | | | | | | | | | | |
Collapse
|