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Yoon Y, Park S, Park T, Kim H, Kim K, Hong J. Enhanced Responsivity and Optoelectronic Properties of Self-Powered Solar-Blind Ag 2O/β-Ga 2O 3 Heterojunction-Based Photodetector with Ag:AZO Co-Sputtered Electrode. Nanomaterials (Basel) 2023; 13:1287. [PMID: 37049380 PMCID: PMC10096629 DOI: 10.3390/nano13071287] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 04/03/2023] [Accepted: 04/03/2023] [Indexed: 06/19/2023]
Abstract
A Ag:AZO electrode was used as an electrode for a self-powered solar-blind ultraviolet photodetector based on a Ag2O/β-Ga2O3 heterojunction. The Ag:AZO electrode was fabricated by co-sputtering Ag and AZO heterogeneous targets using the structural characteristics of a Facing Targets Sputtering (FTS) system with two-facing targets, and the electrical, crystallographic, structural, and optical properties of the fabricated thin film were evaluated. A photodetector was fabricated and evaluated based on the research results that the surface roughness of the electrode can reduce the light energy loss by reducing the scattering and reflectance of incident light energy and improving the trapping phenomenon between interfaces. The thickness of the electrodes was varied from 20 nm to 50 nm depending on the sputtering time. The optoelectronic properties were measured under 254 nm UV-C light, the on/off ratio of the 20 nm Ag:AZO electrode with the lowest surface roughness was 2.01 × 108, and the responsivity and detectivity were 56 mA/W and 6.99 × 1011 Jones, respectively. The Ag2O/β-Ga2O3-based solar-blind photodetector with a newly fabricated top electrode exhibited improved response with self-powered characteristics.
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Wang L, Li H, Zheng J, Li L. Extremely Ultranarrow Linewidth Based on Low-Symmetry Al Nanoellipse Metasurface. Nanomaterials (Basel) 2022; 13:92. [PMID: 36616002 PMCID: PMC9824327 DOI: 10.3390/nano13010092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/14/2022] [Accepted: 12/21/2022] [Indexed: 06/17/2023]
Abstract
Plasmonic nanostructures with ultranarrow linewidths are of great significance in numerous applications, such as optical sensing, surface-enhanced Raman scattering (SERS), and imaging. The traditional plasmonic nanostructures generally consist of gold and silver materials, which are unavailable in the ultraviolet (UV) or deep-ultraviolet (DUV) regions. However, electronic absorption bands of many important biomolecules are mostly located in the UV or DUV regions. Therefore, researchers are eager to realize ultranarrow linewidth of plasmonic nanostructures in these regions. Aluminum (Al) plasmonic nanostructures are potential candidates for realizing the ultranarrow linewidth from the DUV to the near-infrared (NIR) regions. Nevertheless, realizing ultranarrow linewidth below 5 nm remains a challenge in the UV or DUV regions for Al plasmonic nanostructures. In this study, we theoretically designed low-symmetry an Al nanoellipse metasurface on the Al substrate. An ultranarrow linewidth of 1.9 nm has been successfully obtained in the near-UV region (400 nm). Additionally, the ultranarrow linewidth has been successfully modulated to the DUV region by adjusting structural parameters. This work aims to provide a theoretical basis and prediction for the applications, such as UV sensing and UV-SERS.
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Affiliation(s)
| | | | | | - Ling Li
- Correspondence: (J.Z.); (L.L.)
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Jorudas J, Pashnev D, Kašalynas I, Ignatjev I, Niaura G, Selskis A, Astachov V, Alexeeva N. Green Removal of DUV-Polarity-Modified PMMA for Wet Transfer of CVD Graphene. Nanomaterials (Basel) 2022; 12:4017. [PMID: 36432303 PMCID: PMC9697087 DOI: 10.3390/nano12224017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/02/2022] [Accepted: 11/13/2022] [Indexed: 06/16/2023]
Abstract
To fabricate graphene-based high-frequency electronic and optoelectronic devices, there is a high demand for scalable low-contaminated graphene with high mobility. Graphene synthesized via chemical vapor deposition (CVD) on copper foil appears promising for this purpose, but residues from the polymethyl methacrylate (PMMA) layer, used for the wet transfer of CVD graphene, drastically affect the electrical properties of graphene. Here, we demonstrate a scalable and green PMMA removal technique that yields high-mobility graphene on the most common technologically relevant silicon (Si) substrate. As the first step, the polarity of the PMMA was modified under deep-UV irradiation at λ = 254 nm, due to the formation of ketones and aldehydes of higher polarity, which simplifies hydrogen bonding in the step of its dissolution. Modification of PMMA polarity was confirmed by UV and FTIR spectrometry and contact angle measurements. Consecutive dissolution of DUV-exposed PMMA in an environmentally friendly, binary, high-polarity mixture of isopropyl alcohol/water (more commonly alcohol/water) resulted in the rapid and complete removal of DUV-exposed polymers without the degradation of graphene properties, as low-energy exposure does not form free radicals, and thus the released graphene remained intact. The high quality of graphene after PMMA removal was confirmed by SEM, AFM, Raman spectrometry, and by contact and non-contact electrical conductivity measurements. The removal of PMMA from graphene was also performed via other common methods for comparison. The charge carrier mobility in graphene films was found to be up to 6900 cm2/(V·s), demonstrating a high potential of the proposed PMMA removal method in the scalable fabrication of high-performance electronic devices based on CVD graphene.
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Affiliation(s)
- Justinas Jorudas
- THz Photonics Laboratory of Optoelectronics Department, Center for Physical Sciences and Technology (FTMC), Saulėtekis Ave. 3, LT 10257 Vilnius, Lithuania
| | - Daniil Pashnev
- THz Photonics Laboratory of Optoelectronics Department, Center for Physical Sciences and Technology (FTMC), Saulėtekis Ave. 3, LT 10257 Vilnius, Lithuania
| | - Irmantas Kašalynas
- THz Photonics Laboratory of Optoelectronics Department, Center for Physical Sciences and Technology (FTMC), Saulėtekis Ave. 3, LT 10257 Vilnius, Lithuania
| | - Ilja Ignatjev
- Department of Organic Chemistry, Center for Physical Sciences and Technology (FTMC), Saulėtekis Ave. 3, LT 10257 Vilnius, Lithuania
| | - Gediminas Niaura
- Department of Organic Chemistry, Center for Physical Sciences and Technology (FTMC), Saulėtekis Ave. 3, LT 10257 Vilnius, Lithuania
| | - Algirdas Selskis
- Department of Structural Analysis of Materials, Center for Physical Sciences and Technology (FTMC), Saulėtekis Ave. 3, LT 10257 Vilnius, Lithuania
| | - Vladimir Astachov
- Department of Physical Technologies, Center for Physical Sciences and Technology (FTMC), Saulėtekis Ave. 3, LT 10257 Vilnius, Lithuania
| | - Natalia Alexeeva
- THz Photonics Laboratory of Optoelectronics Department, Center for Physical Sciences and Technology (FTMC), Saulėtekis Ave. 3, LT 10257 Vilnius, Lithuania
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Proust V, Kirscher Q, Nguyen TKN, Obringer L, Ishii K, Rault L, Demange V, Berthebaud D, Ohashi N, Uchikoshi T, Berling D, Soppera O, Grasset F. Hafnium Oxide Nanostructured Thin Films: Electrophoretic Deposition Process and DUV Photolithography Patterning. Nanomaterials (Basel) 2022; 12:nano12142334. [PMID: 35889559 PMCID: PMC9320788 DOI: 10.3390/nano12142334] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 06/21/2022] [Accepted: 06/29/2022] [Indexed: 11/16/2022]
Abstract
In the frame of the nanoarchitectonic concept, the objective of this study was to develop simple and easy methods to ensure the preparation of polymorphic HfO2 thin film materials (<200 nm) having the best balance of patterning potential, reproducibility and stability to be used in optical, sensing or electronic fields. The nanostructured HfO2 thin films with micropatterns or continuous morphologies were synthesized by two different methods, i.e., the micropatterning of sol-gel solutions by deep ultraviolet (DUV) photolithography or the electrophoretic deposition (EPD) of HfO2 nanoparticles (HfO2-NPs). Amorphous and monoclinic HfO2 micropatterned nanostructured thin films (HfO2-DUV) were prepared by using a sol-gel solution precursor (HfO2-SG) and spin-coating process following by DUV photolithography, whereas continuous and dense monoclinic HfO2 nanostructured thin films (HfO2-EPD) were prepared by the direct EPD of HfO2-NPs. The HfO2-NPs were prepared by a hydrothermal route and studied through the changing aging temperature, pH and reaction time parameters to produce nanocrystalline particles. Subsequently, based on the colloidal stability study, suspensions of the monoclinic HfO2-NPs with morphologies near spherical, spindle- and rice-like shapes were used to prepare HfO2-EPD thin films on conductive indium-tin oxide-coated glass substrates. Morphology, composition and crystallinity of the HfO2-NPs and thin films were investigated by powder and grazing incidence X-ray diffraction, scanning electron microscopy, transmission electron microscopy and UV-visible spectrophotometry. The EPD and DUV photolithography performances were explored and, in this study, it was clearly demonstrated that these two complementary methods are suitable, simple and effective processes to prepare controllable and tunable HfO2 nanostructures as with homogeneous, dense or micropatterned structures.
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Affiliation(s)
- Vanessa Proust
- CEA, DES, ISEC, DMRC, Université de Montpellier, F-30200 Marcoule, France
- Research Center for Functional Materials, National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan; (K.I.); (N.O.); (T.U.)
- CNRS-Saint Gobain-NIMS, IRL 3629, Laboratory for Innovative Key Materials and Structures (LINK), NIMS, Tsukuba 305-0044, Japan; (T.K.N.N.); (D.B.)
- Correspondence: (V.P.); (O.S.); (F.G.)
| | - Quentin Kirscher
- Université de Haute-Alsace, CNRS, IS2M UMR 7361, F-68100 Mulhouse, France; (Q.K.); (L.O.); (D.B.)
- Université de Strasbourg, F-67081 Strasbourg, France
| | - Thi Kim Ngan Nguyen
- CNRS-Saint Gobain-NIMS, IRL 3629, Laboratory for Innovative Key Materials and Structures (LINK), NIMS, Tsukuba 305-0044, Japan; (T.K.N.N.); (D.B.)
- International Center for Young Scientists, ICYS-Sengen, Global Networking Division, NIMS, Tsukuba 305-0047, Japan
| | - Lisa Obringer
- Université de Haute-Alsace, CNRS, IS2M UMR 7361, F-68100 Mulhouse, France; (Q.K.); (L.O.); (D.B.)
- Université de Strasbourg, F-67081 Strasbourg, France
| | - Kento Ishii
- Research Center for Functional Materials, National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan; (K.I.); (N.O.); (T.U.)
| | - Ludivine Rault
- Univ Rennes, CNRS, ISCR UMR 6226, ScanMAT UAR 2025, F-35000 Rennes, France; (L.R.); (V.D.)
| | - Valérie Demange
- Univ Rennes, CNRS, ISCR UMR 6226, ScanMAT UAR 2025, F-35000 Rennes, France; (L.R.); (V.D.)
| | - David Berthebaud
- CNRS-Saint Gobain-NIMS, IRL 3629, Laboratory for Innovative Key Materials and Structures (LINK), NIMS, Tsukuba 305-0044, Japan; (T.K.N.N.); (D.B.)
| | - Naoki Ohashi
- Research Center for Functional Materials, National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan; (K.I.); (N.O.); (T.U.)
- CNRS-Saint Gobain-NIMS, IRL 3629, Laboratory for Innovative Key Materials and Structures (LINK), NIMS, Tsukuba 305-0044, Japan; (T.K.N.N.); (D.B.)
| | - Tetsuo Uchikoshi
- Research Center for Functional Materials, National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan; (K.I.); (N.O.); (T.U.)
- CNRS-Saint Gobain-NIMS, IRL 3629, Laboratory for Innovative Key Materials and Structures (LINK), NIMS, Tsukuba 305-0044, Japan; (T.K.N.N.); (D.B.)
| | - Dominique Berling
- Université de Haute-Alsace, CNRS, IS2M UMR 7361, F-68100 Mulhouse, France; (Q.K.); (L.O.); (D.B.)
- Université de Strasbourg, F-67081 Strasbourg, France
| | - Olivier Soppera
- Université de Haute-Alsace, CNRS, IS2M UMR 7361, F-68100 Mulhouse, France; (Q.K.); (L.O.); (D.B.)
- Université de Strasbourg, F-67081 Strasbourg, France
- Correspondence: (V.P.); (O.S.); (F.G.)
| | - Fabien Grasset
- CNRS-Saint Gobain-NIMS, IRL 3629, Laboratory for Innovative Key Materials and Structures (LINK), NIMS, Tsukuba 305-0044, Japan; (T.K.N.N.); (D.B.)
- Univ Rennes, CNRS, ISCR UMR 6226, ScanMAT UAR 2025, F-35000 Rennes, France; (L.R.); (V.D.)
- Correspondence: (V.P.); (O.S.); (F.G.)
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Lu S, Luo Z, Li J, Lin W, Chen H, Liu D, Cai D, Huang K, Gao N, Zhou Y, Li S, Kang J. Role of Strain-Induced Microscale Compositional Pulling on Optical Properties of High Al Content AlGaN Quantum Wells for Deep-Ultraviolet LED. Nanoscale Res Lett 2022; 17:13. [PMID: 35032237 PMCID: PMC8760570 DOI: 10.1186/s11671-022-03652-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 01/03/2022] [Indexed: 06/14/2023]
Abstract
A systematic study was carried out for strain-induced microscale compositional pulling effect on the structural and optical properties of high Al content AlGaN multiple quantum wells (MQWs). Investigations reveal that a large tensile strain is introduced during the epitaxial growth of AlGaN MQWs, due to the grain boundary formation, coalescence and growth. The presence of this tensile strain results in the microscale inhomogeneous compositional pulling and Ga segregation, which is further confirmed by the lower formation enthalpy of Ga atom than Al atom on AlGaN slab using first principle simulations. The strain-induced microscale compositional pulling leads to an asymmetrical feature of emission spectra and local variation in emission energy of AlGaN MQWs. Because of a stronger three-dimensional carrier localization, the area of Ga segregation shows a higher emission efficiency compared with the intrinsic area of MQWs, which is benefit for fabricating efficient AlGaN-based deep-ultraviolet light-emitting diode.
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Affiliation(s)
- Shiqiang Lu
- Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, College of Physical Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Zongyan Luo
- Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, College of Physical Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Jinchai Li
- Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, College of Physical Science and Technology, Xiamen University, Xiamen, 361005, China.
| | - Wei Lin
- Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, College of Physical Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Hangyang Chen
- Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, College of Physical Science and Technology, Xiamen University, Xiamen, 361005, China.
| | - Dayi Liu
- Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, College of Physical Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Duanjun Cai
- Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, College of Physical Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Kai Huang
- Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, College of Physical Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Na Gao
- Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, College of Physical Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Yinghui Zhou
- Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, College of Physical Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Shuping Li
- Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, College of Physical Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Junyong Kang
- Fujian Key Laboratory of Semiconductor Materials and Applications, CI Center for OSED, College of Physical Science and Technology, Xiamen University, Xiamen, 361005, China
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Uckert K, Bhartia R, Beegle LW, Monacelli B, Asher SA, Burton AS, Bykov SV, Davis K, Fries MD, Jakubek RS, Hollis JR, Roppel RD, Wu YH. Calibration of the SHERLOC Deep Ultraviolet Fluorescence-Raman Spectrometer on the Perseverance Rover. Appl Spectrosc 2021; 75:763-773. [PMID: 33876994 DOI: 10.1177/00037028211013368] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We describe the wavelength calibration of the spectrometer for the scanning of habitable environments with Raman and luminescence for organics and chemicals (SHERLOC) instrument onboard NASA's Perseverance Rover. SHERLOC utilizes deep ultraviolet Raman and fluorescence (DUV R/F) spectroscopy to enable analysis of samples from the Martian surface. SHERLOC employs a 248.6 nm deep ultraviolet laser to generate Raman-scattered photons and native fluorescence emission photons from near-surface material to detect and classify chemical and mineralogical compositions. The collected photons are focused on a charge-coupled device and the data are returned to Earth for analysis. The compact DUV R/F spectrometer has a spectral range from 249.9 nm to 353.6 nm (∼200 cm-1 to 12 000 cm-1) (with a spectral resolution of 0.296 nm (∼40 cm-1)). The compact spectrometer uses a custom design to project a high-resolution Raman spectrum and a low-resolution fluorescence spectrum on a single charge-coupled device. The natural spectral separation enabled by deep ultraviolet excitation enables wavelength separation of the Raman/fluorescence spectra. The SHERLOC spectrometer was designed to optimize the resolution of the Raman spectral region and the wavelength range of the fluorescence region. The resulting illumination on the charge-coupled device is curved, requiring a segmented, nonlinear wavelength calibration in order to understand the mineralogy and chemistry of Martian materials.
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Affiliation(s)
- Kyle Uckert
- Jet Propulsion Laboratory California Institution of Technology, Pasadena, CA, USA
| | | | - Luther W Beegle
- Jet Propulsion Laboratory California Institution of Technology, Pasadena, CA, USA
| | - Brian Monacelli
- Jet Propulsion Laboratory California Institution of Technology, Pasadena, CA, USA
| | - Sanford A Asher
- University of Pittsburgh Chemistry Department, Pittsburgh, PA, USA
| | | | - Sergei V Bykov
- University of Pittsburgh Chemistry Department, Pittsburgh, PA, USA
| | | | - Marc D Fries
- 43834NASA Johnson Space Center, Houston, TX, USA
| | | | | | - Ryan D Roppel
- University of Pittsburgh Chemistry Department, Pittsburgh, PA, USA
| | - Yen-Hung Wu
- Jet Propulsion Laboratory California Institution of Technology, Pasadena, CA, USA
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Hao X, Luo M, Lin C, Peng G, Xu F, Ye N. M(NH 2 SO 3 ) 2 (M=Sr, Ba): Two Deep-Ultraviolet Transparent Sulfamates Exhibiting Strong Second Harmonic Generation Responses and Moderate Birefringence. Angew Chem Int Ed Engl 2021; 60:7621-7625. [PMID: 33470036 DOI: 10.1002/anie.202016372] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 01/14/2021] [Indexed: 11/10/2022]
Abstract
Over the last few decades, the development of each new nonlinear optical (NLO)-active functional unit has led to the discoveries of a series of excellent NLO materials. In the present work, based on first-principles studies, we identified a novel deep-UV (DUV) NLO-active functional unit, a non-π-conjugated group viz. (NH2 SO3 )- . By combining alkaline-earth metals with (NH2 SO3 )- group, two DUV transparent NLO sulfamates, M(NH2 SO3 )2 (M=Sr, Ba) with superior optical properties including strong SHG responses (1.2 and 2.7 × KH2 PO4 (KDP)), short UV cut-off edge (<190 nm) and moderate birefringence (0.056@589.3 nm for Sr(NH2 SO3 )2 ) were successfully synthesized. Our work has provided not only two promising DUV transparent NLO crystals, but also an innovative non-π-conjugated unit for developing more DUV transparent NLO materials.
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Affiliation(s)
- Xia Hao
- Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China.,School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.,University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Min Luo
- Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China
| | - Chensheng Lin
- Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China
| | - Guang Peng
- Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China
| | - Feng Xu
- Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China
| | - Ning Ye
- Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China.,Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, 350002, China
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Khalil HMW, Khan MF, Eom J, Noh H. Highly Stable and Tunable Chemical Doping of Multilayer WS2 Field Effect Transistor: Reduction in Contact Resistance. ACS Appl Mater Interfaces 2015; 7:23589-23596. [PMID: 26434774 DOI: 10.1021/acsami.5b06825] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The development of low resistance contacts to 2D transition-metal dichalcogenides (TMDs) is still a big challenge for the future generation field effect transistors (FETs) and optoelectronic devices. Here, we report a chemical doping technique to achieve low contact resistance by keeping the intrinsic properties of few layers WS2. The transfer length method has been used to investigate the effect of chemical doping on contact resistance. After doping, the contact resistance (Rc) of multilayer (ML) WS2 has been reduced to 0.9 kΩ·μm. The significant reduction of the Rc is mainly due to the high electron doping density, thus a reduction in Schottky barrier height, which limits the device performance. The threshold voltage of ML-WS2 FETs confirms a negative shift upon the chemical doping, as further confirmed from the positions of E(1)2g and A1g peaks in Raman spectra. The n-doped samples possess a high drain current of 65 μA/μm, with an on/off ratio of 1.05 × 10(6) and a field effect mobility of 34.7 cm(2)/(V·s) at room temperature. Furthermore, the photoelectric properties of doped WS2 flakes were also measured under deep ultraviolet light. The potential of using LiF doping in contact engineering of TMDs opens new ways to improve the device performance.
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Affiliation(s)
- Hafiz M W Khalil
- Department of Physics and Graphene Research Institute, Sejong University , Seoul 143-747, Korea
| | - Muhammad Farooq Khan
- Department of Physics and Graphene Research Institute, Sejong University , Seoul 143-747, Korea
| | - Jonghwa Eom
- Department of Physics and Graphene Research Institute, Sejong University , Seoul 143-747, Korea
| | - Hwayong Noh
- Department of Physics and Graphene Research Institute, Sejong University , Seoul 143-747, Korea
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