51
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Kim YC, Nguyen VT, Lee S, Park JY, Ahn YH. Evaluation of Transport Parameters in MoS 2/Graphene Junction Devices Fabricated by Chemical Vapor Deposition. ACS APPLIED MATERIALS & INTERFACES 2018; 10:5771-5778. [PMID: 29355012 DOI: 10.1021/acsami.7b16177] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We demonstrated imaging of the depletion layer in a MoS2/graphene heterojunction fabricated by chemical vapor deposition and obtained their transport parameters such as diffusion length, lifetime, and mobility by using scanning photocurrent microscopy (SPCM). The device exhibited a n-type operation, which was determined by the MoS2 layer with a lower mobility. The SPCM revealed the presence of the depletion layer at the heterojunction, whereas graphene provided an excellent electrical contact for the MoS2 layer without resulting in a rectifying behavior, even if they were anchored within a very short range. The polarity of the photocurrent signal switched when we applied a drain-source bias voltage, from which we extracted the potential barrier at the junction. More importantly, a bias-dependent SPCM allowed us to simultaneously record the diffusion lengths of both majority and minority carriers for the respective MoS2 and graphene layers. By combining the diffusion lengths with the lifetimes measured by femtosecond SPCM, we determined the electron and hole mobilities in each layer, from which we found that the electron mobility (160 cm2 V-1 s-1) was higher than the hole mobility (80 cm2 V-1 s-1) in MoS2, whereas the hole mobility (15 000 cm2 V-1 s-1) was relatively higher in graphene.
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Affiliation(s)
- Young Chul Kim
- Department of Physics and Department of Energy Systems Research, Ajou University , Suwon 16499, Korea
| | - Van Tu Nguyen
- Department of Physics and Department of Energy Systems Research, Ajou University , Suwon 16499, Korea
| | - Soonil Lee
- Department of Physics and Department of Energy Systems Research, Ajou University , Suwon 16499, Korea
| | - Ji-Yong Park
- Department of Physics and Department of Energy Systems Research, Ajou University , Suwon 16499, Korea
| | - Yeong Hwan Ahn
- Department of Physics and Department of Energy Systems Research, Ajou University , Suwon 16499, Korea
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52
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Chen K, Roy A, Rai A, Valsaraj A, Meng X, He F, Xu X, Register LF, Banerjee S, Wang Y. Carrier Trapping by Oxygen Impurities in Molybdenum Diselenide. ACS APPLIED MATERIALS & INTERFACES 2018; 10:1125-1131. [PMID: 29226670 DOI: 10.1021/acsami.7b15478] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Understanding defect effect on carrier dynamics is essential for both fundamental physics and potential applications of transition metal dichalcogenides (TMDs). Here, the phenomenon of oxygen impurities trapping photoexcited carriers has been studied with ultrafast pump-probe spectroscopy. Oxygen impurities are intentionally created in exfoliated multilayer MoSe2 with Ar+ plasma irradiation and air exposure. After plasma treatment, the signal of transient absorption first increases and then decreases, which is a signature of defect-capturing carriers. With larger density of oxygen defects, the trapping effect becomes more prominent. The trapping defect densities are estimated from the transient absorption signal, and its increasing trend in the longer-irradiated sample agrees with the results from X-ray photoelectron spectroscopy. First-principle calculations with density functional theory reveal that oxygen atoms occupying Mo vacancies create mid-gap defect states, which are responsible for carrier trapping. Our findings shed light on the important role of oxygen defects as carrier trappers in TMDs, and facilitate defect engineering in relevant materials and device applications.
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Affiliation(s)
| | - Anupam Roy
- Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin , Austin, Texas 78758, United States
| | - Amritesh Rai
- Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin , Austin, Texas 78758, United States
| | - Amithraj Valsaraj
- Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin , Austin, Texas 78758, United States
| | | | | | - Xiaochuan Xu
- Omega Optics, Inc. , Austin, Texas 78757, United States
| | - Leonard F Register
- Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin , Austin, Texas 78758, United States
| | - Sanjay Banerjee
- Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin , Austin, Texas 78758, United States
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53
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Dubey S, Lisi S, Nayak G, Herziger F, Nguyen VD, Le Quang T, Cherkez V, González C, Dappe YJ, Watanabe K, Taniguchi T, Magaud L, Mallet P, Veuillen JY, Arenal R, Marty L, Renard J, Bendiab N, Coraux J, Bouchiat V. Weakly Trapped, Charged, and Free Excitons in Single-Layer MoS 2 in the Presence of Defects, Strain, and Charged Impurities. ACS NANO 2017; 11:11206-11216. [PMID: 28992415 DOI: 10.1021/acsnano.7b05520] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Few- and single-layer MoS2 host substantial densities of defects. They are thought to influence the doping level, the crystal structure, and the binding of electron-hole pairs. We disentangle the concomitant spectroscopic expression of all three effects and identify to what extent they are intrinsic to the material or extrinsic to it, i.e., related to its local environment. We do so by using different sources of MoS2-a natural one and one prepared at high pressure and high temperature-and different substrates bringing varying amounts of charged impurities and by separating the contributions of internal strain and doping in Raman spectra. Photoluminescence unveils various optically active excitonic complexes. We discover a defect-bound state having a low binding energy of 20 meV that does not appear sensitive to strain and doping, unlike charged excitons. Conversely, the defect does not significantly dope or strain MoS2. Scanning tunneling microscopy and density functional theory simulations point to substitutional atoms, presumably individual nitrogen atoms at the sulfur site. Our work shows the way to a systematic understanding of the effect of external and internal fields on the optical properties of two-dimensional materials.
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Affiliation(s)
- Sudipta Dubey
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Simone Lisi
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Goutham Nayak
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Felix Herziger
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Van-Dung Nguyen
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Toai Le Quang
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Vladimir Cherkez
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - César González
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay , 91191 Gif-sur-Yvette Cedex, France
- Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autonoma de Madrid , E-28049 Madrid, Spain
| | - Yannick J Dappe
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay , 91191 Gif-sur-Yvette Cedex, France
| | - Kenji Watanabe
- National Institute for Materials Science , Tsukuba, 305-0044, Japan
| | | | - Laurence Magaud
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Pierre Mallet
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Jean-Yves Veuillen
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Raul Arenal
- Laboratorio de Microscopiías Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza , 50018 Zaragoza, Spain
- ARAID Foundation , 50018 Zaragoza, Spain
| | - Laëtitia Marty
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Julien Renard
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Nedjma Bendiab
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Johann Coraux
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
| | - Vincent Bouchiat
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel , 38000 Grenoble, France
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54
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Lin MF, Kochat V, Krishnamoorthy A, Bassman Oftelie L, Weninger C, Zheng Q, Zhang X, Apte A, Tiwary CS, Shen X, Li R, Kalia R, Ajayan P, Nakano A, Vashishta P, Shimojo F, Wang X, Fritz DM, Bergmann U. Ultrafast non-radiative dynamics of atomically thin MoSe 2. Nat Commun 2017; 8:1745. [PMID: 29170416 PMCID: PMC5701075 DOI: 10.1038/s41467-017-01844-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 10/20/2017] [Indexed: 11/08/2022] Open
Abstract
Photo-induced non-radiative energy dissipation is a potential pathway to induce structural-phase transitions in two-dimensional materials. For advancing this field, a quantitative understanding of real-time atomic motion and lattice temperature is required. However, this understanding has been incomplete due to a lack of suitable experimental techniques. Here, we use ultrafast electron diffraction to directly probe the subpicosecond conversion of photoenergy to lattice vibrations in a model bilayered semiconductor, molybdenum diselenide. We find that when creating a high charge carrier density, the energy is efficiently transferred to the lattice within one picosecond. First-principles nonadiabatic quantum molecular dynamics simulations reproduce the observed ultrafast increase in lattice temperature and the corresponding conversion of photoenergy to lattice vibrations. Nonadiabatic quantum simulations further suggest that a softening of vibrational modes in the excited state is involved in efficient and rapid energy transfer between the electronic system and the lattice.
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Affiliation(s)
- Ming-Fu Lin
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Vidya Kochat
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
| | - Aravind Krishnamoorthy
- Collaboratory for Advanced Computing and Simulations, Department of Physics & Astronomy, Department of Computer Science, Department of Chemical Engineering & Materials Science, Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089-0242, USA
| | - Lindsay Bassman Oftelie
- Collaboratory for Advanced Computing and Simulations, Department of Physics & Astronomy, Department of Computer Science, Department of Chemical Engineering & Materials Science, Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089-0242, USA
| | - Clemens Weninger
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Qiang Zheng
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Xiang Zhang
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
| | - Amey Apte
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
| | - Chandra Sekhar Tiwary
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
| | - Xiaozhe Shen
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Renkai Li
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Rajiv Kalia
- Collaboratory for Advanced Computing and Simulations, Department of Physics & Astronomy, Department of Computer Science, Department of Chemical Engineering & Materials Science, Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089-0242, USA
| | - Pulickel Ajayan
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
| | - Aiichiro Nakano
- Collaboratory for Advanced Computing and Simulations, Department of Physics & Astronomy, Department of Computer Science, Department of Chemical Engineering & Materials Science, Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089-0242, USA
| | - Priya Vashishta
- Collaboratory for Advanced Computing and Simulations, Department of Physics & Astronomy, Department of Computer Science, Department of Chemical Engineering & Materials Science, Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089-0242, USA
| | - Fuyuki Shimojo
- Department of Physics, Kumamoto University, Kumamoto, 860-8555, Japan
| | - Xijie Wang
- SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - David M Fritz
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Uwe Bergmann
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
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55
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Pesci FM, Sokolikova MS, Grotta C, Sherrell PC, Reale F, Sharda K, Ni N, Palczynski P, Mattevi C. MoS2/WS2 Heterojunction for Photoelectrochemical Water Oxidation. ACS Catal 2017. [DOI: 10.1021/acscatal.7b01517] [Citation(s) in RCA: 160] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Federico M. Pesci
- Department of Materials, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Maria S. Sokolikova
- Department of Materials, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Chiara Grotta
- Department of Materials, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Peter C. Sherrell
- Department of Materials, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Francesco Reale
- Department of Materials, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Kanudha Sharda
- Department of Materials, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Na Ni
- Department of Materials, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Pawel Palczynski
- Department of Materials, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Cecilia Mattevi
- Department of Materials, Imperial College London, London, SW7 2AZ, United Kingdom
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56
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McKenna AJ, Eliason JK, Flannigan DJ. Spatiotemporal Evolution of Coherent Elastic Strain Waves in a Single MoS 2 Flake. NANO LETTERS 2017; 17:3952-3958. [PMID: 28510457 DOI: 10.1021/acs.nanolett.7b01565] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We use bright-field imaging in an ultrafast electron microscope to spatiotemporally map the evolution of photoexcited coherent strain waves in a single, micrometer-size flake of MoS2. Following in situ femtosecond photoexcitation, we observe individual wave trains emerge from discrete nanoscale morphological features and propagate in-plane along specific wave vectors at approximately the speed of sound (7 nm/ps). Over the span of several hundred picoseconds, the 50 GHz wave trains (20 ps periods) are observed to undergo phonon-phonon scattering and wave-train interference, resulting in a transition to larger-scale, incoherent structural dynamics. This incoherent motion further evolves into coherent nanomechanical oscillations over a few nanoseconds, ultimately leading to megahertz, whole-flake multimode resonances having microsecond lifetimes. These results provide insight into the low-frequency structural response of MoS2 to relatively coherent optical photoexcitation by elucidating the origin and the evolution of high-velocity, gigahertz strain waves.
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Affiliation(s)
- Alyssa J McKenna
- Department of Chemical Engineering and Materials Science, University of Minnesota , 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
| | - Jeffrey K Eliason
- Department of Chemical Engineering and Materials Science, University of Minnesota , 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota , 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
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57
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Pradhan NR, Talapatra S, Terrones M, Ajayan PM, Balicas L. Optoelectronic Properties of Heterostructures: The Most Recent Developments Based on Graphene and Transition-Metal Dichalcogenides. IEEE NANOTECHNOLOGY MAGAZINE 2017. [DOI: 10.1109/mnano.2017.2676185] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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58
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Zheng Z, Yao J, Yang G. Centimeter-Scale Deposition of Mo 0.5W 0.5Se 2 Alloy Film for High-Performance Photodetectors on Versatile Substrates. ACS APPLIED MATERIALS & INTERFACES 2017; 9:14920-14928. [PMID: 28406009 DOI: 10.1021/acsami.7b02166] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Because of their great potential for academic investigation and practical application in next-generation optoelectronic devices, ternary layered semiconductors have attracted considerable attention in recent years. Similar to the applications of traditional layered materials, practical applications of ternary layered semiconductor alloys require the synthesis of large-area samples. Here, we report the preparation of centimeter-scale and high-quality Mo0.5W0.5Se2 alloy films on both a rigid SiO2/Si substrate and a flexible polyimide (PI) substrate. Then, photodetectors based on these alloy films are fabricated, which are capable of conducting broad-band photodetection from ultraviolet to near-infrared region (370-808 nm) with high performance. The photodetector on SiO2/Si substrates demonstrates a high responsivity (R) of 77.1 A/W, an outstanding detectivity (D*) of 1.1 × 1012 Jones, and a fast response time of 8.3 ms. These figures-of-merit are much superior to those of the counterparts of binary material-based devices. Moreover, the photodetector on PI substrates also achieves high performance (R = 63.5 A/W, D* = 3.56 × 1012 Jones). And no apparent degradation in the device properties is observed even after 100 bending cycles. These results make Mo0.5W0.5Se2 alloy a highly qualified candidate for next-generation optoelectronic applications.
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Affiliation(s)
- Zhaoqiang Zheng
- State Key Laboratory of Optoelectronic Materials and Technologies, Nanotechnology Research Center, School of Materials Science & Engineering, Sun Yat-sen University , Guangzhou 510275, Guangdong, P. R. China
| | - Jiandong Yao
- State Key Laboratory of Optoelectronic Materials and Technologies, Nanotechnology Research Center, School of Materials Science & Engineering, Sun Yat-sen University , Guangzhou 510275, Guangdong, P. R. China
| | - Guowei Yang
- State Key Laboratory of Optoelectronic Materials and Technologies, Nanotechnology Research Center, School of Materials Science & Engineering, Sun Yat-sen University , Guangzhou 510275, Guangdong, P. R. China
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59
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Jiang D, Du X, Zhou L, Li H, Wang K. New Insights toward Efficient Charge-Separation Mechanism for High-Performance Photoelectrochemical Aptasensing: Enhanced Charge-Carrier Lifetime via Coupling Ultrathin MoS 2 Nanoplates with Nitrogen-Doped Graphene Quantum Dots. Anal Chem 2017; 89:4525-4531. [PMID: 28337919 DOI: 10.1021/acs.analchem.6b04949] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Deeply understanding the internal mechanism of the photoelectrohemical (PEC) process is conducive to fabricate high-performance PEC biosensors. In this work, we proposed a new insight toward an efficient charge-separation mechanism in high-performance PEC biosensors. Specifically, we disclosed that the lifetimes of photogenerated charge carriers of ultrathin MoS2 nanosheets could be prolonged by approximately millisecond time scales after a proper mole ratio of NGQDs were coupled, leading to the promoted charge separation and a giant photocurrent signal magnification. Benefiting from the dramatic signal amplification and the introduction of acetamiprid aptamer, subfemtomolar level detection of acetamiprid is achieved, which makes our strategy among the most sensitive electronic approaches for PEC-based monitoring of targets. This study was beneficial to further understand the charge-separation mechanism in PEC biosensing, which paved the way for the development of more efficient PEC biosensors.
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Affiliation(s)
- Ding Jiang
- School of Food and Biological Engineering, Jiangsu University , Zhenjiang 212013, P.R. China
| | - Xiaojiao Du
- Key Laboratory of Modern Agriculture Equipment and Technology, School of Chemistry and Chemical Engineering, Jiangsu University , Zhenjiang 212013, P.R. China
| | - Lei Zhou
- Key Laboratory of Modern Agriculture Equipment and Technology, School of Chemistry and Chemical Engineering, Jiangsu University , Zhenjiang 212013, P.R. China
| | - Henan Li
- Key Laboratory of Modern Agriculture Equipment and Technology, School of Chemistry and Chemical Engineering, Jiangsu University , Zhenjiang 212013, P.R. China
| | - Kun Wang
- Key Laboratory of Modern Agriculture Equipment and Technology, School of Chemistry and Chemical Engineering, Jiangsu University , Zhenjiang 212013, P.R. China
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60
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Shastry TA, Balla I, Bergeron H, Amsterdam SH, Marks TJ, Hersam MC. Mutual Photoluminescence Quenching and Photovoltaic Effect in Large-Area Single-Layer MoS 2-Polymer Heterojunctions. ACS NANO 2016; 10:10573-10579. [PMID: 27783505 DOI: 10.1021/acsnano.6b06592] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Two-dimensional transition metal dichalcogenides (TMDCs) have recently attracted attention due to their superlative optical and electronic properties. In particular, their extraordinary optical absorption and semiconducting band gap have enabled demonstrations of photovoltaic response from heterostructures composed of TMDCs and other organic or inorganic materials. However, these early studies were limited to devices at the micrometer scale and/or failed to exploit the unique optical absorption properties of single-layer TMDCs. Here we present an experimental realization of a large-area type-II photovoltaic heterojunction using single-layer molybdenum disulfide (MoS2) as the primary absorber, by coupling it to the organic π-donor polymer PTB7. This TMDC-polymer heterojunction exhibits photoluminescence intensity that is tunable as a function of the thickness of the polymer layer, ultimately enabling complete quenching of the TMDC photoluminescence. The strong optical absorption in the TMDC-polymer heterojunction produces an internal quantum efficiency exceeding 40% for an overall cell thickness of less than 20 nm, resulting in exceptional current density per absorbing thickness in comparison to other organic and inorganic solar cells. Furthermore, this work provides insight into the recombination processes in type-II TMDC-polymer heterojunctions and thus provides quantitative guidance to ongoing efforts to realize efficient TMDC-based solar cells.
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Affiliation(s)
- Tejas A Shastry
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Argonne-Northwestern Solar Energy Research Center, Northwestern University , Evanston, Illinois 60208, United States
| | - Itamar Balla
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Argonne-Northwestern Solar Energy Research Center, Northwestern University , Evanston, Illinois 60208, United States
| | - Hadallia Bergeron
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Argonne-Northwestern Solar Energy Research Center, Northwestern University , Evanston, Illinois 60208, United States
| | - Samuel H Amsterdam
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Argonne-Northwestern Solar Energy Research Center, Northwestern University , Evanston, Illinois 60208, United States
| | - Tobin J Marks
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Argonne-Northwestern Solar Energy Research Center, Northwestern University , Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, ‡Department of Chemistry, and §Argonne-Northwestern Solar Energy Research Center, Northwestern University , Evanston, Illinois 60208, United States
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61
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Lee D, Hwang E, Lee Y, Choi Y, Kim JS, Lee S, Cho JH. Multibit MoS 2 Photoelectronic Memory with Ultrahigh Sensitivity. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:9196-9202. [PMID: 27562539 DOI: 10.1002/adma.201603571] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Indexed: 06/06/2023]
Abstract
A novel multibit MoS2 photoelectronic nonvolatile memory device is developed by synergistically combining rational device designs and the efficient transfer of large-area MoS2 flakes. The MoS2 photoelectronic memory exhibits excellent memory characteristics, including a large programming/erasing current ratio that exceeds 107 , multilevel data storage of 3 bits (corresponding to eight levels), performance stability over 200 cycles, and stable data retention over 104 s.
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Affiliation(s)
- Dain Lee
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 440-746, Korea
| | - Euyheon Hwang
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 440-746, Korea
- Department of Physics, Sungkyunkwan University, Suwon, 440-746, Korea
| | - Youngbin Lee
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 440-746, Korea
| | - Yongsuk Choi
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 440-746, Korea
| | - Jong Su Kim
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 440-746, Korea
| | - Seungwoo Lee
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 440-746, Korea
- School of Chemical Engineering, Sungkyunkwan University, Suwon, 440-746, Korea
| | - Jeong Ho Cho
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 440-746, Korea.
- School of Chemical Engineering, Sungkyunkwan University, Suwon, 440-746, Korea.
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62
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Agnihotri P, Dhakras P, Lee JU. Bipolar Junction Transistors in Two-Dimensional WSe2 with Large Current and Photocurrent Gains. NANO LETTERS 2016; 16:4355-4360. [PMID: 27336742 DOI: 10.1021/acs.nanolett.6b01444] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In the development of semiconductor devices, the bipolar junction transistor (BJT) features prominently as being the first solid state transistor that helped to usher in the digital revolution. For any new semiconductor, therefore, the fabrication and characterization of the BJT are important for both technological importance and historical significance. Here, we demonstrate a BJT device in exfoliated TMD semiconductor WSe2. We use buried gates to electrostatically create doped regions with back-to-back p-n junctions. We demonstrate two central characteristics of a bipolar device: current gain when operated as a BJT and a photocurrent gain when operated as a phototransistor. We demonstrate a current gain of 1000 and photocurrent gain of 40 and describe features that enhance these properties due to the doping technique that we employ.
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Affiliation(s)
- Pratik Agnihotri
- Colleges of Nanoscale Science and Engineering, SUNY-Polytechnic Institute , Albany, New York 12203, United States
| | - Prathamesh Dhakras
- Colleges of Nanoscale Science and Engineering, SUNY-Polytechnic Institute , Albany, New York 12203, United States
| | - Ji Ung Lee
- Colleges of Nanoscale Science and Engineering, SUNY-Polytechnic Institute , Albany, New York 12203, United States
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Moody G, Schaibley J, Xu X. Exciton Dynamics in Monolayer Transition Metal Dichalcogenides. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. B, OPTICAL PHYSICS 2016; 33:C39-C49. [PMID: 28890600 PMCID: PMC5590662 DOI: 10.1364/josab.33.000c39] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Since the discovery of semiconducting monolayer transition metal dichalcogenides, a variety of experimental and theoretical studies have been carried out seeking to understand the intrinsic exciton population recombination and valley relaxation dynamics. Reports of the exciton decay time range from hundreds of femtoseconds to ten nanoseconds, while the valley depolarization time can exceed one nanosecond. At present, however, a consensus on the microscopic mechanisms governing exciton radiative and non-radiative recombination is lacking. The strong exciton oscillator strength resulting in up to ~ 20% absorption for a single monolayer points to ultrafast radiative recombination. However, the low quantum yield and large variance in the reported lifetimes suggest that non-radiative Auger-type processes obscure the intrinsic exciton radiative lifetime. In either case, the electron-hole exchange interaction plays an important role in the exciton spin and valley dynamics. In this article, we review the experiments and theory that have led to these conclusions and comment on future experiments that could complement our current understanding.
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Affiliation(s)
- Galan Moody
- National Institute of Standards & Technology, 325 Broadway, Boulder, CO 80305
- Corresponding author:
| | - John Schaibley
- Department of Physics, University of Washington, Seattle, Washington 98195
| | - Xiaodong Xu
- Department of Physics, University of Washington, Seattle, Washington 98195
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195
- Corresponding author:
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Yao J, Zheng Z, Yang G. Promoting the Performance of Layered-Material Photodetectors by Alloy Engineering. ACS APPLIED MATERIALS & INTERFACES 2016; 8:12915-12924. [PMID: 27152481 DOI: 10.1021/acsami.6b03691] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The successful peeling of graphene heralded the era of van der Waals material (vdWM) electronics. However, photodetectors based on semiconducting transition metal dichalcogenides (TMDs), formulated as MX2 (M = Mo, W; X = S, Se), often suffer either poor responsivity or long response time because of their high density of deep-level defect states (DLDSs). Alloy engineering, which can shift the DLDSs to shallow-level defect states, is proposed to be an efficient strategy to solve this problem. However, proof-of-concept is still lacking, which is probably because of the absence of a facile technology to grow high-quality alloyed TMDs. Here, we report the growth of large-scale and high-quality Mo0.5W0.5S2 alloy films via pulsed laser deposition (PLD). We demonstrate that the resulting Mo0.5W0.5S2 photodetector possesses a stable photoresponse from 370 to 1064 nm. The photocurrent exhibits positive dependence on both the source-drain voltage and incident power density, providing good tunability for multifunctional photoelectrical applications. We also establish that, because of the suppression of DLDSs with alloy engineering, the Mo0.5W0.5S2 photodetector achieves a good responsivity of 5.8 A/W and a response time shorter than 150 ms. The working mechanism for the suppression of DLDSs in Mo0.5W0.5S2 is unveiled by qualitatively analyzing the alloying-dressed band structure. In conclusion, the excellent performance of the PLD-grown Mo0.5W0.5S2 photodetector may pave the way for next-generation photodetection. The approach shown here represents a fundamental and universal scenario for the development of alloyed TMDs.
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Affiliation(s)
- Jiandong Yao
- State Key Laboratory of Optoelectronic Materials and Technologies, Nanotechnology Research Center, School of Materials Science & Engineering, Sun Yat-sen University , Guangzhou 510275, Guangdong, P. R. China
| | - Zhaoqiang Zheng
- State Key Laboratory of Optoelectronic Materials and Technologies, Nanotechnology Research Center, School of Materials Science & Engineering, Sun Yat-sen University , Guangzhou 510275, Guangdong, P. R. China
| | - Guowei Yang
- State Key Laboratory of Optoelectronic Materials and Technologies, Nanotechnology Research Center, School of Materials Science & Engineering, Sun Yat-sen University , Guangzhou 510275, Guangdong, P. R. China
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