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Chung CH, Lin CY, Liu HY, Nian SE, Chen YT, Tsai CE. Impact of Rh, Ru, and Pd Leads and Contact Topologies on Performance of WSe 2 FETs: A First Comparative Ab Initio Study. MATERIALS (BASEL, SWITZERLAND) 2024; 17:2665. [PMID: 38893929 PMCID: PMC11173614 DOI: 10.3390/ma17112665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 05/10/2024] [Accepted: 05/23/2024] [Indexed: 06/21/2024]
Abstract
2D field-effect transistors (FETs) fabricated with transition metal dichalcogenide (TMD) materials are a potential replacement for the silicon-based CMOS. However, the lack of advancement in p-type contact is also a key factor hindering TMD-based CMOS applications. The less investigated path towards improving electrical characteristics based on contact geometries with low contact resistance (RC) has also been established. Moreover, finding contact metals to reduce the RC is indeed one of the significant challenges in achieving the above goal. Our research provides the first comparative analysis of the three contact configurations for a WSe2 monolayer with different noble metals (Rh, Ru, and Pd) by employing ab initio density functional theory (DFT) and non-equilibrium Green's function (NEGF) methods. From the perspective of the contact topologies, the RC and minimum subthreshold slope (SSMIN) of all the conventional edge contacts are outperformed by the novel non-van der Waals (vdW) sandwich contacts. These non-vdW sandwich contacts reveal that their RC values are below 50 Ω∙μm, attributed to the narrow Schottky barrier widths (SBWs) and low Schottky barrier heights (SBHs). Not only are the RC values dramatically reduced by such novel contacts, but the SSMIN values are lower than 68 mV/dec. The new proposal offers the lowest RC and SSMIN, irrespective of the contact metals. Further considering the metal leads, the WSe2/Rh FETs based on the non-vdW sandwich contacts show a meager RC value of 33 Ω∙μm and an exceptional SSMIN of 63 mV/dec. The two calculated results present the smallest-ever values reported in our study, indicating that the non-vdW sandwich contacts with Rh leads can attain the best-case scenario. In contrast, the symmetric convex edge contacts with Pd leads cause the worst-case degradation, yielding an RC value of 213 Ω∙μm and an SSMIN value of 95 mV/dec. While all the WSe2/Ru FETs exhibit medium performances, the minimal shift in the transfer curves is interestingly advantageous to the circuit operation. Conclusively, the low-RC performances and the desirable SSMIN values are a combination of the contact geometries and metal leads. This innovation, achieved through noble metal leads in conjunction with the novel contact configurations, paves the way for a TMD-based CMOS with ultra-low RC and rapid switching speeds.
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Affiliation(s)
| | - Chiung-Yuan Lin
- Department of Electronics and Electrical Engineering and Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan; (C.-H.C.); (H.-Y.L.); (S.-E.N.); (Y.-T.C.); (C.-E.T.)
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Chung CH, Chen TY, Lin CY, Chien HW. Ultrashort channel MoSe 2transistors with selenium atoms replaced at the interface: first-principles quantum-transport study. NANOTECHNOLOGY 2024; 35:175709. [PMID: 38176068 DOI: 10.1088/1361-6528/ad1afa] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 01/04/2024] [Indexed: 01/06/2024]
Abstract
Realizing n- and p-type transition metal dichalcogenide (TMD)-based field-effect transistors for nanoscale complementary metal oxide semiconductor (CMOS) applications remains challenging owing to undesirable contact resistance. Quantumtransport calculations were performed by replacing single-sided Se atoms of TMD near the interface with As or Br atoms to further improve the contact resistance. Here, partial selenium replacement produced a novel interface with a segment of metamaterial MoSeX (Pt/MoSeX/MoSe2; X = As, Br). Such stable metamaterials exhibit semi-metallicity, and the contact resistance can be thus lowered. Our findings provide insights into the potential of MoSe2-based nano-CMOS logic devices.
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Affiliation(s)
- Chih-Hung Chung
- Department of Electronics and Electrical Engineering and Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Ting-Yu Chen
- Department of Electronics and Electrical Engineering and Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Chiung-Yuan Lin
- Department of Electronics and Electrical Engineering and Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
| | - Huang-Wei Chien
- Department of Electronics and Electrical Engineering and Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
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3
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Marian D, Marin EG, Perucchini M, Iannaccone G, Fiori G. Multi-scale simulations of two dimensional material based devices: the NanoTCAD ViDES suite. JOURNAL OF COMPUTATIONAL ELECTRONICS 2023; 22:1327-1337. [PMID: 37840652 PMCID: PMC10567950 DOI: 10.1007/s10825-023-02048-2] [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: 01/31/2023] [Accepted: 04/16/2023] [Indexed: 10/17/2023]
Abstract
NanoTCAD ViDES (Versatile DEvice Simulator) is an open-source suite of computing codes aimed at assessing the operation and the performance of nanoelectronic devices. It has served the computational nanoelectronic community for almost two decades and it is freely available to researchers around the world in its website (http://vides.nanotcad.com), being employed in hundreds of works by many electronic device simulation groups worldwide. We revise the code structure and its main modules and we present the new features directed towards (i) multi-scale approaches exploiting ab-initio electron-structure calculations, aiming at the exploitation of new physics in electronic devices, (ii) the inclusion of arbitrary heterostructures of layered materials to devise original device architectures and operation, and (iii) the exploration of novel low-cost, green technologies in the mesoscopic scale, as, e.g. printed electronics.
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Affiliation(s)
- Damiano Marian
- Dipartimento di Ingegneria dell’Informazione, Università di Pisa, Via G. Caruso 16, 16122 Pisa, Italy
| | - Enrique G. Marin
- Departmento de Electrónica, Universidad de Granada, Avenida Fuente Nueva s/n, 18071 Granada, Spain
| | - Marta Perucchini
- Dipartimento di Ingegneria dell’Informazione, Università di Pisa, Via G. Caruso 16, 16122 Pisa, Italy
| | - Giuseppe Iannaccone
- Dipartimento di Ingegneria dell’Informazione, Università di Pisa, Via G. Caruso 16, 16122 Pisa, Italy
| | - Gianluca Fiori
- Dipartimento di Ingegneria dell’Informazione, Università di Pisa, Via G. Caruso 16, 16122 Pisa, Italy
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4
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Cheng Z, Backman J, Zhang H, Abuzaid H, Li G, Yu Y, Cao L, Davydov AV, Luisier M, Richter CA, Franklin AD. Distinct Contact Scaling Effects in MoS 2 Transistors Revealed with Asymmetrical Contact Measurements. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2210916. [PMID: 36848627 DOI: 10.1002/adma.202210916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 02/15/2023] [Indexed: 05/26/2023]
Abstract
2D semiconducting materials have immense potential for future electronics due to their atomically thin nature, which enables better scalability. While the channel scalability of 2D materials has been extensively studied, the current understanding of contact scaling in 2D devices is inconsistent and oversimplified. Here physically scaled contacts and asymmetrical contact measurements (ACMs) are combined to investigate the contact scaling behavior in 2D field-effect transistors. The ACMs directly compare electron injection at different contact lengths while using the exact same MoS2 channel, eliminating channel-to-channel variations. The results show that scaled source contacts can limit the drain current, whereas scaled drain contacts do not. Compared to devices with long contact lengths, devices with short contact lengths (scaled contacts) exhibit larger variations, 15% lower drain currents at high drain-source voltages, and a higher chance of early saturation and negative differential resistance. Quantum transport simulations reveal that the transfer length of Ni-MoS2 contacts can be as short as 5 nm. Furthermore, it is clearly identified that the actual transfer length depends on the quality of the metal-2D interface. The ACMs demonstrated here will enable further understanding of contact scaling behavior at various interfaces.
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Affiliation(s)
- Zhihui Cheng
- Department of Electrical & Computer Engineering, Duke University, Durham, NC, 27708, USA
- Department of Electrical & Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA
- Nanoscale Device Characterization Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Jonathan Backman
- Integrated Systems Laboratory, ETH Zurich, Zurich, CH-8092, Switzerland
| | - Huairuo Zhang
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
- Theiss Research, Inc., La Jolla, California, 92037, USA
| | - Hattan Abuzaid
- Department of Electrical & Computer Engineering, Duke University, Durham, NC, 27708, USA
| | - Guoqing Li
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, 27695, USA
| | - Yifei Yu
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, 27695, USA
| | - Linyou Cao
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, 27695, USA
| | - Albert V Davydov
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Mathieu Luisier
- Integrated Systems Laboratory, ETH Zurich, Zurich, CH-8092, Switzerland
| | - Curt A Richter
- Nanoscale Device Characterization Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Aaron D Franklin
- Department of Electrical & Computer Engineering, Duke University, Durham, NC, 27708, USA
- Department of Chemistry, Duke University, Durham, NC, 27708, USA
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Chen M, Peng B, Sporea RA, Podzorov V, Chan PKL. The Origin of Low Contact Resistance in Monolayer Organic Field‐Effect Transistors with van der Waals Electrodes. SMALL SCIENCE 2022. [DOI: 10.1002/smsc.202100115] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- Ming Chen
- Department of Mechanical Engineering The University of Hong Kong Pok Fu Lam Road Hong Kong China
| | - Boyu Peng
- Department of Mechanical Engineering The University of Hong Kong Pok Fu Lam Road Hong Kong China
| | - Radu A. Sporea
- Department of Electrical and Electronic Engineering Advanced Technology Institute University of Surrey Guildford GU2 7XH UK
| | - Vitaly Podzorov
- Department of Physics and Astronomy Rutgers University Piscataway 08854 NJ USA
| | - Paddy Kwok Leung Chan
- Department of Mechanical Engineering The University of Hong Kong Pok Fu Lam Road Hong Kong China
- Advanced Biomedical Instrumentation Centre Hong Kong Science Park Shatin Hong Kong China
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Weinbub J, Kosik R. Computational perspective on recent advances in quantum electronics: from electron quantum optics to nanoelectronic devices and systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:163001. [PMID: 35008077 DOI: 10.1088/1361-648x/ac49c6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Accepted: 01/10/2022] [Indexed: 06/14/2023]
Abstract
Quantum electronics has significantly evolved over the last decades. Where initially the clear focus was on light-matter interactions, nowadays approaches based on the electron's wave nature have solidified themselves as additional focus areas. This development is largely driven by continuous advances in electron quantum optics, electron based quantum information processing, electronic materials, and nanoelectronic devices and systems. The pace of research in all of these areas is astonishing and is accompanied by substantial theoretical and experimental advancements. What is particularly exciting is the fact that the computational methods, together with broadly available large-scale computing resources, have matured to such a degree so as to be essential enabling technologies themselves. These methods allow to predict, analyze, and design not only individual physical processes but also entire devices and systems, which would otherwise be very challenging or sometimes even out of reach with conventional experimental capabilities. This review is thus a testament to the increasingly towering importance of computational methods for advancing the expanding field of quantum electronics. To that end, computational aspects of a representative selection of recent research in quantum electronics are highlighted where a major focus is on the electron's wave nature. By categorizing the research into concrete technological applications, researchers and engineers will be able to use this review as a source for inspiration regarding problem-specific computational methods.
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Affiliation(s)
- Josef Weinbub
- Christian Doppler Laboratory for High Performance TCAD, Institute for Microelectronics, TU Wien, Austria
| | - Robert Kosik
- Institute for Microelectronics, TU Wien, Austria
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Lu W, Liu L, Zhu T, Li Z, Shao M, Zhang C, Yu J, Zhao X, Yang C, Li Z. MoS 2/graphene van der Waals heterojunctions combined with two-layered Au NP for SERS and catalysis analyse. OPTICS EXPRESS 2021; 29:38053-38067. [PMID: 34808865 DOI: 10.1364/oe.443835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 10/22/2021] [Indexed: 06/13/2023]
Abstract
MoS2-plasmonic hybrid platforms have attracted significant interest in surface-enhanced Raman scattering (SERS) and plasmon-driven photocatalysis. However, direct contact between the metal and MoS2 creates strain that deteriorates the electron transport across the metal/ MoS2 interfaces, which would affect the SERS effect and the catalytic performance. Here, the MoS2/graphene van der Waals heterojunctions (vdWHs) were fabricated and combined with two-layered gold nanoparticles (Au NP) for SERS and plasmon-driven photocatalysis analyse. The graphene film is introduced to provide an effective buffer layer between Au NP and MoS2, which not only eliminates the inhomogeneous contact on MoS2 but also benefits the electron transfer. The substrate exhibits excellent SERS capability realizing ultra-sensitive detection for 4-pyridinethiol molecules. Also, the surface catalytic reaction of p-nitrothiophenol (PNTP) to p,p-dimercaptobenzene (DMAB) conversion was in situ monitored, demonstrating that the vdWHs-plasmonic hybrid could effectively accelerate reaction process. The mechanism of the SERS and catalytic behaviors are investigated via experiments combined with theoretical simulations (finite element method and quantum chemical calculations).
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Physical insights on transistors based on lateral heterostructures of monolayer and multilayer PtSe 2 via Ab initio modelling of interfaces. Sci Rep 2021; 11:18482. [PMID: 34531506 PMCID: PMC8446074 DOI: 10.1038/s41598-021-98080-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 08/23/2021] [Indexed: 11/08/2022] Open
Abstract
Lateral heterostructures (LH) of monolayer-multilayer regions of the same noble transition metal dichalcogenide, such as platinum diselenide (PtSe2), are promising options for the fabrication of efficient two-dimensional field-effect transistors (FETs), by exploiting the dependence of the energy gap on the number of layers and the intrinsically high quality of the heterojunctions. Key for future progress in this direction is understanding the effects of the physics of the lateral interfaces on far-from-equilibrium transport properties. In this work, a multi-scale approach to device simulation, capable to include ab-initio modelling of the interfaces in a computationally efficient way, is presented. As an application, p- and n-type monolayer-multilayer PtSe2 LH-FETs are investigated, considering design parameters such as channel length, number of layers and junction quality. The simulations suggest that such transistors can provide high performance in terms of subthreshold characteristics and switching behavior, and that a single channel device is not capable, even in the ballistic defectless limit, to satisfy the requirements of the semiconductor roadmap for the next decade, and that stacked channel devices would be required. It is shown how ab-initio modelling of interfaces provides a reliable physical description of charge displacements in their proximity, which can be crucial to correctly predict device transport properties, especially in presence of strong dipoles, mixed stoichiometries or imperfections.
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Sun Y, Niu G, Ren W, Meng X, Zhao J, Luo W, Ye ZG, Xie YH. Hybrid System Combining Two-Dimensional Materials and Ferroelectrics and Its Application in Photodetection. ACS NANO 2021; 15:10982-11013. [PMID: 34184877 DOI: 10.1021/acsnano.1c01735] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Photodetectors are one of the most important components for a future "Internet-of-Things" information society. Compared to the mainstream semiconductor-based photodetectors, emerging devices based on two-dimensional (2D) materials and ferroelectrics as well as their hybrid systems have been extensively studied in recent decades due to their outstanding performances and related interesting physical, electrical, and optoelectronic phenomena. In this paper, we review the photodetection based on 2D materials and ferroelectric hybrid systems. The fundamentals of 2D and ferroelectric materials as well as the interaction in the hybrid system will be introduced. Ferroelectricity modulated optoelectronic properties in the hybrid system will be discussed in detail. After the basics and figures of merit of photodetectors are summarized, the 2D-ferroelectrics devices with different structures including p-n diodes, Schottky diodes, and field-effect transistors will be reviewed and compared. The polarization of ferroelectrics offers the possibility of the modulation and enhancement of the photodetection in the hybrid detectors, which will be discussed in depth. Finally, the challenges and perspectives of the photodetectors based on 2D ferroelectrics will be proposed. This Review outlines the important aspects of the recent development of the hybrid system of 2D and ferroelectric materials, which could interact with each other and thus lead to photodetectors with higher performances. Such a Review will be helpful for the research of emerging physical phenomena and for the design of multifunctional nanoscale electronic and optoelectronic devices.
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Affiliation(s)
- Yanxiao Sun
- Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an 710049, Shaanxi, P. R. China
| | - Gang Niu
- Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an 710049, Shaanxi, P. R. China
| | - Wei Ren
- Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an 710049, Shaanxi, P. R. China
| | - Xiangjian Meng
- National Laboratory for Infrared Physics Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, P. R. China
| | - Jinyan Zhao
- Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education & International Center for Dielectric Research, School of Electronic Science and Engineering, Xi'an Jiaotong University, No. 28, Xianning West Road, Xi'an 710049, Shaanxi, P. R. China
| | - Wenbo Luo
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 611731, P. R. China
| | - Zuo-Guang Ye
- Department of Chemistry and 4D Laboratories, Simon Fraser University, Burnaby V5A 1S6, British Columbia, Canada
| | - Ya-Hong Xie
- Department of Materials Science and Engineering, University of California Los Angeles, Los Angeles 90024, California, United States
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10
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Impact of device scaling on the electrical properties of MoS 2 field-effect transistors. Sci Rep 2021; 11:6610. [PMID: 33758215 PMCID: PMC7987965 DOI: 10.1038/s41598-021-85968-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/04/2021] [Indexed: 11/08/2022] Open
Abstract
Two-dimensional semiconducting materials are considered as ideal candidates for ultimate device scaling. However, a systematic study on the performance and variability impact of scaling the different device dimensions is still lacking. Here we investigate the scaling behavior across 1300 devices fabricated on large-area grown MoS2 material with channel length down to 30 nm, contact length down to 13 nm and capacitive effective oxide thickness (CET) down to 1.9 nm. These devices show best-in-class performance with transconductance of 185 μS/μm and a minimum subthreshold swing (SS) of 86 mV/dec. We find that scaling the top-contact length has no impact on the contact resistance and electrostatics of three monolayers MoS2 transistors, because edge injection is dominant. Further, we identify that SS degradation occurs at short channel length and can be mitigated by reducing the CET and lowering the Schottky barrier height. Finally, using a power performance area (PPA) analysis, we present a roadmap of material improvements to make 2D devices competitive with silicon gate-all-around devices.
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McClellan CJ, Yalon E, Smithe KKH, Suryavanshi SV, Pop E. High Current Density in Monolayer MoS 2 Doped by AlO x. ACS NANO 2021; 15:1587-1596. [PMID: 33405894 DOI: 10.1021/acsnano.0c09078] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Semiconductors require stable doping for applications in transistors, optoelectronics, and thermoelectrics. However, this has been challenging for two-dimensional (2D) materials, where existing approaches are either incompatible with conventional semiconductor processing or introduce time-dependent, hysteretic behavior. Here we show that low-temperature (<200 °C) substoichiometric AlOx provides a stable n-doping layer for monolayer MoS2, compatible with circuit integration. This approach achieves carrier densities >2 × 1013 cm-2, sheet resistance as low as ∼7 kΩ/□, and good contact resistance ∼480 Ω·μm in transistors from monolayer MoS2 grown by chemical vapor deposition. We also reach record current density of nearly 700 μA/μm (>110 MA/cm2) along this three-atom-thick semiconductor while preserving transistor on/off current ratio >106. The maximum current is ultimately limited by self-heating (SH) and could exceed 1 mA/μm with better device heat sinking. With their 0.1 nA/μm off-current, such doped MoS2 devices approach several low-power transistor metrics required by the international technology roadmap.
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Affiliation(s)
- Connor J McClellan
- Electrical Engineering, Stanford University, Stanford, California 94305, United States
| | - Eilam Yalon
- Electrical Engineering, Stanford University, Stanford, California 94305, United States
| | - Kirby K H Smithe
- Electrical Engineering, Stanford University, Stanford, California 94305, United States
| | - Saurabh V Suryavanshi
- Electrical Engineering, Stanford University, Stanford, California 94305, United States
| | - Eric Pop
- Electrical Engineering, Stanford University, Stanford, California 94305, United States
- Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
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Maji TK, J R A, Mukherjee S, Alexander R, Mondal A, Das S, Sharma RK, Chakraborty NK, Dasgupta K, Sharma AMR, Hawaldar R, Pandey M, Naik A, Majumdar K, Pal SK, Adarsh KV, Ray SK, Karmakar D. Combinatorial Large-Area MoS 2/Anatase-TiO 2 Interface: A Pathway to Emergent Optical and Optoelectronic Functionalities. ACS APPLIED MATERIALS & INTERFACES 2020; 12:44345-44359. [PMID: 32864953 DOI: 10.1021/acsami.0c13342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The interface of transition-metal dichalcogenides (TMDCs) and high-k dielectric transition-metal oxides (TMOs) had triggered umpteen discourses because of the indubitable impact of TMOs in reducing the contact resistances and restraining the Fermi-level pinning for the metal-TMDC contacts. In the present work, we focus on the unresolved tumults of large-area TMDC/TMO interfaces, grown by adopting different techniques. Here, on a pulsed laser-deposited MoS2 thin film, a layer of TiO2 is grown by atomic layer deposition (ALD) and pulsed laser deposition (PLD). These two different techniques emanate the layer of TiO2 with different crystallinities, thicknesses, and interfacial morphologies, subsequently influencing the electronic and optical properties of the interfaces. Contrasting the earlier reports of n-type doping at the exfoliated MoS2/TiO2 interfaces, the large-area MoS2/anatase-TiO2 films had realized a p-type doping of the underneath MoS2, manifesting a boost in the extent of p-type doping with increasing thickness of TiO2, as emerged from the X-ray photoelectron spectra. Density functional analysis of the MoS2/anatase-TiO2 interfaces, with pristine and interfacial defect configurations, could correlate the interdependence of doping and the terminating atomic surface of TiO2 on MoS2. The optical properties of the interface, encompassing photoluminescence, transient absorption and z-scan two-photon absorption, indicate the presence of defect-induced localized midgap levels in MoS2/TiO2 (PLD) and a relatively defect-free interface in MoS2/TiO2 (ALD), corroborating nicely with the corresponding theoretical analysis. From the investigation of optical properties, we indicate that the MoS2/TiO2 (PLD) interface may act as a promising saturable absorber, having a significant nonlinear response for the sub-band-gap excitations. Moreover, the MoS2/TiO2 (PLD) interface had exemplified better phototransport properties. A potential application of MoS2/TiO2 (PLD) is demonstrated by the fabrication of a p-type phototransistor with the ionic-gel top gate. This endeavor to analyze and perceive the MoS2/TiO2 interface establishes the prospectives of large-area interfaces in the field of optics and optoelectronics.
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Affiliation(s)
- Tuhin Kumar Maji
- Department of Chemical Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Sector III, JD Block, Kolkata 700106, India
| | - Aswin J R
- Department of Physics, Indian Institute of Science Education and Research, Bhopal 462066, India
| | | | - Rajath Alexander
- Advanced Carbon Materials Section, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Anirban Mondal
- Department of Physics, Indian Institute of Science Education and Research, Bhopal 462066, India
| | - Sarthak Das
- Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Rajendra Kumar Sharma
- Raja Rammana Centre for Advance Technology, Parmanu Nagar, Sahkar Nagar Extension, 1, CAT Rd, Rajendra Nagar, Indore, Madhya Pradesh 45201, India
| | | | - Kinshuk Dasgupta
- Advanced Carbon Materials Section, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Anjanashree M R Sharma
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Ranjit Hawaldar
- Centre for Materials for Electronics Technology, Off Pashan Road, Panchwati, Pune 411008, India
| | - Manjiri Pandey
- Accelerator Control Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Akshay Naik
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Kausik Majumdar
- Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Samir Kumar Pal
- Department of Chemical Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Sector III, JD Block, Kolkata 700106, India
| | - K V Adarsh
- Department of Physics, Indian Institute of Science Education and Research, Bhopal 462066, India
| | - Samit Kumar Ray
- Department of Chemical Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Sector III, JD Block, Kolkata 700106, India
- Department of Physics, IIT Kharagpur, Kharagpur, West Bengal 721302, India
| | - Debjani Karmakar
- Technical Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
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13
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Somvanshi D, Ber E, Bailey CS, Pop E, Yalon E. Improved Current Density and Contact Resistance in Bilayer MoSe 2 Field Effect Transistors by AlO x Capping. ACS APPLIED MATERIALS & INTERFACES 2020; 12:36355-36361. [PMID: 32678569 PMCID: PMC7588022 DOI: 10.1021/acsami.0c09541] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Atomically thin semiconductors are of interest for future electronics applications, and much attention has been given to monolayer (1L) sulfides, such as MoS2, grown by chemical vapor deposition (CVD). However, reports on the electrical properties of CVD-grown selenides, and MoSe2 in particular, are scarce. Here, we compare the electrical properties of 1L and bilayer (2L) MoSe2 grown by CVD and capped by sub-stoichiometric AlOx. The 2L channels exhibit ∼20× lower contact resistance (RC) and ∼30× larger current density compared with 1L channels. RC is further reduced by >5× with AlOx capping, which enables improved transistor current density. Overall, 2L AlOx-capped MoSe2 transistors (with ∼500 nm channel length) achieve improved current density (∼65 μA/μm at VDS = 4 V), a good Ion/Ioff ratio of >106, and an RC of ∼60 kΩ·μm. The weaker performance of 1L devices is due to their sensitivity to processing and ambient. Our results suggest that 2L (or few layers) is preferable to 1L for improved electronic properties in applications that do not require a direct band gap, which is a key finding for future two-dimensional electronics.
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Affiliation(s)
- Divya Somvanshi
- Viterbi
Department of Electrical Engineering, Technion-Israel
Institute of Technology, Haifa 32000, Israel
| | - Emanuel Ber
- Viterbi
Department of Electrical Engineering, Technion-Israel
Institute of Technology, Haifa 32000, Israel
| | - Connor S. Bailey
- Department
of Electrical Engineering, Stanford University, Stanford, California 94305, United States
| | - Eric Pop
- Department
of Electrical Engineering, Stanford University, Stanford, California 94305, United States
- Department
of Materials Science & Engineering, Stanford University, Stanford, California 94305, United States
- Precourt
Institute for Energy, Stanford University, Stanford, California 94305, United States
| | - Eilam Yalon
- Viterbi
Department of Electrical Engineering, Technion-Israel
Institute of Technology, Haifa 32000, Israel
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Klinkert C, Szabó Á, Stieger C, Campi D, Marzari N, Luisier M. 2-D Materials for Ultrascaled Field-Effect Transistors: One Hundred Candidates under the Ab Initio Microscope. ACS NANO 2020; 14:8605-8615. [PMID: 32530608 DOI: 10.1021/acsnano.0c02983] [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
Due to their remarkable properties, single-layer 2-D materials appear as excellent candidates to extend Moore's scaling law beyond the currently manufactured silicon FinFETs. However, the known 2-D semiconducting components, essentially transition metal dichalcogenides, are still far from delivering the expected performance. Based on a recent theoretical study that predicts the existence of more than 1800 exfoliable 2-D materials, we investigate here the 100 most promising contenders for logic applications. Their current versus voltage characteristics are simulated from first-principles, combining density functional theory and advanced quantum transport calculations. Both n- and p-type configurations are considered, with gate lengths ranging from 15 down to 5 nm. From this large collection of electronic materials, we identify 13 compounds with electron and hole currents potentially much higher than those in future Si FinFETs. The resulting database widely expands the design space of 2-D transistors and provides original guidelines to the materials and device engineering community.
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Affiliation(s)
- Cedric Klinkert
- Integrated System Laboratory, ETH Zurich, CH-8092 Zurich, Switzerland
| | - Áron Szabó
- Integrated System Laboratory, ETH Zurich, CH-8092 Zurich, Switzerland
| | - Christian Stieger
- Integrated System Laboratory, ETH Zurich, CH-8092 Zurich, Switzerland
| | - Davide Campi
- Theory and Simulation of Materials (THEOS) and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Nicola Marzari
- Theory and Simulation of Materials (THEOS) and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Mathieu Luisier
- Integrated System Laboratory, ETH Zurich, CH-8092 Zurich, Switzerland
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15
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Jain A, Szabó Á, Parzefall M, Bonvin E, Taniguchi T, Watanabe K, Bharadwaj P, Luisier M, Novotny L. One-Dimensional Edge Contacts to a Monolayer Semiconductor. NANO LETTERS 2019; 19:6914-6923. [PMID: 31513426 DOI: 10.1021/acs.nanolett.9b02166] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Integration of electrical contacts into van der Waals (vdW) heterostructures is critical for realizing electronic and optoelectronic functionalities. However, to date no scalable methodology for gaining electrical access to buried monolayer two-dimensional (2D) semiconductors exists. Here we report viable edge contact formation to hexagonal boron nitride (hBN) encapsulated monolayer MoS2. By combining reactive ion etching, in situ Ar+ sputtering and annealing, we achieve a relatively low edge contact resistance, high mobility (up to ∼30 cm2 V-1 s-1) and high on-current density (>50 μA/μm at VDS = 3V), comparable to top contacts. Furthermore, the atomically smooth hBN environment also preserves the intrinsic MoS2 channel quality during fabrication, leading to a steep subthreshold swing of 116 mV/dec with a negligible hysteresis. Hence, edge contacts are highly promising for large-scale practical implementation of encapsulated heterostructure devices, especially those involving air sensitive materials, and can be arbitrarily narrow, which opens the door to further shrinkage of 2D device footprint.
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Affiliation(s)
- Achint Jain
- Photonics Laboratory , ETH Zürich , 8093 Zürich , Switzerland
| | - Áron Szabó
- Integrated Systems Laboratory , ETH Zürich , 8092 Zürich , Switzerland
| | | | - Eric Bonvin
- Photonics Laboratory , ETH Zürich , 8093 Zürich , Switzerland
| | - Takashi Taniguchi
- National Institute for Material Science , 1-1 Namiki , Tsukuba 305-0044 , Japan
| | - Kenji Watanabe
- National Institute for Material Science , 1-1 Namiki , Tsukuba 305-0044 , Japan
| | - Palash Bharadwaj
- Department of Electrical and Computer Engineering , Rice University , Houston , Texas 77005 , United States
| | - Mathieu Luisier
- Integrated Systems Laboratory , ETH Zürich , 8092 Zürich , Switzerland
| | - Lukas Novotny
- Photonics Laboratory , ETH Zürich , 8093 Zürich , Switzerland
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