1
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Strand J, Shluger AL. On the Structure of Oxygen Deficient Amorphous Oxide Films. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2306243. [PMID: 38148443 PMCID: PMC10885675 DOI: 10.1002/advs.202306243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 12/05/2023] [Indexed: 12/28/2023]
Abstract
Understanding defects in amorphous oxide films and heterostructures is vital to improving performance of microelectronic devices, thin-film transistors, and electrocatalysis. However, to what extent the structure and properties of point defects in amorphous solids are similar to those in the crystalline phase are still debated. The validity of this analogy and the experimental and theoretical evidence of the effects of oxygen deficiency in amorphous oxide films are critically discussed. The authors start with the meaning and significance of defect models, such as "oxygen vacancy" in crystalline oxides, and then introduce experimental and computational methods used to study intrinsic defects in amorphous oxides and discuss their limitations and challenges. To test the validity of existing defect models, ab initio molecular dynamics is used with a non-local density functional to model the structure and electronic properties of oxygen-deficient amorphous alumina. Unlike some previous studies, the formation of deep defect states in the bandgap caused by the oxygen deficiency is found. Apart from atomistic structures analogous to crystal vacancies, the formation of more stable defect states characterized by the bond formation between under-coordinated Al ions is shown. The limitations of such defect models and how they may be overcome in simulations are discussed.
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Affiliation(s)
- Jack Strand
- Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK
- Nanolayers Research Computing Ltd., London, UK
| | - Alexander L Shluger
- Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK
- WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
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2
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Ravichandran H, Knobloch T, Pannone A, Karl A, Stampfer B, Waldhoer D, Zheng Y, Sakib NU, Karim Sadaf MU, Pendurthi R, Torsi R, Robinson JA, Grasser T, Das S. Observation of Rich Defect Dynamics in Monolayer MoS 2. ACS NANO 2023. [PMID: 37490390 DOI: 10.1021/acsnano.2c12900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
Defects play a pivotal role in limiting the performance and reliability of nanoscale devices. Field-effect transistors (FETs) based on atomically thin two-dimensional (2D) semiconductors such as monolayer MoS2 are no exception. Probing defect dynamics in 2D FETs is therefore of significant interest. Here, we present a comprehensive insight into various defect dynamics observed in monolayer MoS2 FETs at varying gate biases and temperatures. The measured source-to-drain currents exhibit random telegraph signals (RTS) owing to the transfer of charges between the semiconducting channel and individual defects. Based on the modeled temperature and gate bias dependence, oxygen vacancies or aluminum interstitials are probable defect candidates. Several types of RTSs are observed including anomalous RTS and giant RTS indicating local current crowding effects and rich defect dynamics in monolayer MoS2 FETs. This study explores defect dynamics in large area-grown monolayer MoS2 with ALD-grown Al2O3 as the gate dielectric.
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Affiliation(s)
- Harikrishnan Ravichandran
- Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
| | - Theresia Knobloch
- Institute for Microelectronics (TU Wien), Gusshausstrasse 27-29, 1040 Vienna, Austria
| | - Andrew Pannone
- Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
| | - Alexander Karl
- Institute for Microelectronics (TU Wien), Gusshausstrasse 27-29, 1040 Vienna, Austria
| | - Bernhard Stampfer
- Institute for Microelectronics (TU Wien), Gusshausstrasse 27-29, 1040 Vienna, Austria
| | - Dominic Waldhoer
- Institute for Microelectronics (TU Wien), Gusshausstrasse 27-29, 1040 Vienna, Austria
| | - Yikai Zheng
- Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
| | - Najam U Sakib
- Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
| | - Muhtasim Ul Karim Sadaf
- Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
| | - Rahul Pendurthi
- Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
| | - Riccardo Torsi
- Materials Science and Engineering, Penn State University, University Park, Pennsylvania 16802, United States
| | - Joshua A Robinson
- Materials Science and Engineering, Penn State University, University Park, Pennsylvania 16802, United States
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
- Department of Physics, Penn State University, University Park, Pennsylvania 16802, United States
| | - Tibor Grasser
- Institute for Microelectronics (TU Wien), Gusshausstrasse 27-29, 1040 Vienna, Austria
| | - Saptarshi Das
- Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802, United States
- Materials Science and Engineering, Penn State University, University Park, Pennsylvania 16802, United States
- Materials Research Institute, Penn State University, University Park, Pennsylvania 16802, United States
- Electrical Engineering, Penn State University, University Park, Pennsylvania 16802, United States
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3
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Christie JK. Review: understanding the properties of amorphous materials with high-performance computing methods. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2023; 381:20220251. [PMID: 37211037 DOI: 10.1098/rsta.2022.0251] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 03/20/2023] [Indexed: 05/23/2023]
Abstract
Amorphous materials have no long-range order in their atomic structure. This makes much of the formalism for the study of crystalline materials irrelevant, and so elucidating their structure and properties is challenging. The use of computational methods is a powerful complement to experimental studies, and in this paper we review the use of high-performance computing methods in the simulation of amorphous materials. Five case studies are presented to showcase the wide range of materials and computational methods available to practitioners in this field. This article is part of a discussion meeting issue 'Supercomputing simulations of advanced materials'.
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Affiliation(s)
- J K Christie
- Department of Materials, Loughborough University, Loughborough LE11 3TU, UK
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4
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Bian Z, Miao J, Zhang T, Chen H, Zhu Q, Chai J, Tian F, Wu S, Xu Y, Yu B, Chai Y, Zhao Y. Carrier Modulation in 2D Transistors by Inserting Interfacial Dielectric Layer for Area-Efficient Computation. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023:e2206791. [PMID: 37010037 DOI: 10.1002/smll.202206791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 03/05/2023] [Indexed: 06/19/2023]
Abstract
2D materials with atomic thickness display strong gate controllability and emerge as promising materials to build area-efficient electronic circuits. However, achieving the effective and nondestructive modulation of carrier density/type in 2D materials is still challenging because the introduction of dopants will greatly degrade the carrier transport via Coulomb scattering. Here, a strategy to control the polarity of tungsten diselenide (WSe2 ) field-effect transistors (FETs) via introducing hexagonal boron nitride (h-BN) as the interfacial dielectric layer is devised. By modulating the h-BN thickness, the carrier type of WSe2 FETs has been switched from hole to electron. The ultrathin body of WSe2 , combined with the effective polarity control, together contribute to the versatile single-transistor logic gates, including NOR, AND, and XNOR gates, and the operation of only two transistors as a half adder in logic circuits. Compared with the use of 12 transistors based on static Si CMOS technology, the transistor number of the half adder is reduced by 83.3%. The unique carrier modulation approach has general applicability toward 2D logic gates and circuits for the improvement of area efficiency in logic computation.
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Affiliation(s)
- Zheng Bian
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, China
| | - Jialei Miao
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, China
| | - Tianjiao Zhang
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, China
| | - Haohan Chen
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, China
| | - Qinghai Zhu
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, China
| | - Jian Chai
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, China
| | - Feng Tian
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, China
| | - Shaoxiong Wu
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, China
| | - Yang Xu
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, China
| | - Bin Yu
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, China
| | - Yang Chai
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, 999077, China
| | - Yuda Zhao
- School of Micro-Nano Electronics, Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, China
- Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, Jianghan University, Wuhan, 430056, China
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5
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Gao D, Shenoy R, Yi S, Lee J, Xu M, Rong Z, Deo A, Nathan D, Zheng JG, Williams RS, Chen Y. Synaptic Resistor Circuits Based on Al Oxide and Ti Silicide for Concurrent Learning and Signal Processing in Artificial Intelligence Systems. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2210484. [PMID: 36779432 DOI: 10.1002/adma.202210484] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 01/10/2023] [Indexed: 06/18/2023]
Abstract
Neurobiological circuits containing synapses can process signals while learning concurrently in real time. Before an artificial neural network (ANN) can execute a signal-processing program, it must first be programmed by humans or trained with respect to a large and defined data set during learning processes, resulting in significant latency, high power consumption, and poor adaptability to unpredictable changing environments. In this work, a crossbar circuit of synaptic resistors (synstors) is reported, each synstor integrating a Si channel with an Al oxide memory layer and Ti silicide Schottky contacts. Individual synstors are characterized and analyzed to understand their concurrent signal-processing and learning abilities. Without any prior training, synstor circuits concurrently execute signal processing and learning in real time to fly drones toward a target position in an aerodynamically changing environment faster than human controllers, and with learning speed, performance, power consumption, and adaptability to the environment significantly superior to an ANN running on computers. The synstor circuit provides a path to establish power-efficient intelligent systems with real-time learning and adaptability in the capriciously mutable real world.
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Affiliation(s)
- Dawei Gao
- Departments of Mechanical and Aerospace Engineering, Materials Science and Engineering, Electrical and Computer Engineering, California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Rahul Shenoy
- Departments of Mechanical and Aerospace Engineering, Materials Science and Engineering, Electrical and Computer Engineering, California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Suin Yi
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Jungmin Lee
- Departments of Mechanical and Aerospace Engineering, Materials Science and Engineering, Electrical and Computer Engineering, California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Mingjie Xu
- Irvine Materials Research Institute, University of California, Irvine, Irvine, CA, 92697-2800, USA
| | - Zixuan Rong
- Departments of Mechanical and Aerospace Engineering, Materials Science and Engineering, Electrical and Computer Engineering, California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Atharva Deo
- Departments of Mechanical and Aerospace Engineering, Materials Science and Engineering, Electrical and Computer Engineering, California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Dhruva Nathan
- Departments of Mechanical and Aerospace Engineering, Materials Science and Engineering, Electrical and Computer Engineering, California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Jian-Guo Zheng
- Irvine Materials Research Institute, University of California, Irvine, Irvine, CA, 92697-2800, USA
| | - R Stanley Williams
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Yong Chen
- Departments of Mechanical and Aerospace Engineering, Materials Science and Engineering, Electrical and Computer Engineering, California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA
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6
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Pugliese A, Shyam B, Repa GM, Nguyen AH, Mehta A, Webb III EB, Fredin LA, Strandwitz NC. Atomic-Layer-Deposited Aluminum Oxide Thin Films Probed with X-ray Scattering and Compared to Molecular Dynamics and Density Functional Theory Models. ACS OMEGA 2022; 7:41033-41043. [PMID: 36406558 PMCID: PMC9670265 DOI: 10.1021/acsomega.2c04402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 10/12/2022] [Indexed: 06/16/2023]
Abstract
A better understanding of amorphous aluminum oxide's structure and electronic properties is obtained through combined experimental and computational approaches. Grazing incidence X-ray scattering measurements were carried out on aluminum oxide thin films grown using thermal atomic layer deposition. The corresponding pair distribution functions (PDFs) showed structures similar to previously reported PDFs of solid-state amorphous alumina and molten alumina. Structural models based on crystalline alumina polymorphs (PDFgui) and amorphous alumina (molecular dynamics, MD) were examined for structural comparisons to the experimental PDF data. Smaller MD models were optimized and verified against larger models to allow for quantum chemical electronic structure calculations. The electronic structure of the amorphous alumina models yields additional insight into the band structure and electronic defects present in amorphous alumina that are not present in crystalline samples.
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Affiliation(s)
- Anthony Pugliese
- Materials
Science and Engineering Department, Lehigh
University, Bethlehem, Pennsylvania 18015, USA
| | - Badri Shyam
- Xerion
Advanced Battery Corporation, Kettering, Ohio 45420, USA
| | - Gil M. Repa
- Chemistry
Department, Lehigh University, Bethlehem, Pennsylvania 18015, USA
| | - Anh Hung Nguyen
- Mechanical
Engineering and Mechanics Department, Lehigh
University, Bethlehem, Pennsylvania 18015, USA
| | - Apurva Mehta
- SLAC
National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Edmund B. Webb III
- Mechanical
Engineering and Mechanics Department, Lehigh
University, Bethlehem, Pennsylvania 18015, USA
| | - Lisa A. Fredin
- Chemistry
Department, Lehigh University, Bethlehem, Pennsylvania 18015, USA
| | - Nicholas C. Strandwitz
- Materials
Science and Engineering Department, Lehigh
University, Bethlehem, Pennsylvania 18015, USA
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7
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Zheng F, Beleggia M, Migunov V, Pozzi G, Dunin-Borkowski RE. Electron-beam-induced charging of an Al 2O3 nanotip studied using off-axis electron holography. Ultramicroscopy 2022; 241:113593. [DOI: 10.1016/j.ultramic.2022.113593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 07/16/2022] [Accepted: 07/21/2022] [Indexed: 10/31/2022]
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8
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Knobloch T, Uzlu B, Illarionov YY, Wang Z, Otto M, Filipovic L, Waltl M, Neumaier D, Lemme MC, Grasser T. Improving stability in two-dimensional transistors with amorphous gate oxides by Fermi-level tuning. NATURE ELECTRONICS 2022; 5:356-366. [PMID: 35783488 PMCID: PMC9236902 DOI: 10.1038/s41928-022-00768-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 04/22/2022] [Indexed: 06/02/2023]
Abstract
Electronic devices based on two-dimensional semiconductors suffer from limited electrical stability because charge carriers originating from the semiconductors interact with defects in the surrounding insulators. In field-effect transistors, the resulting trapped charges can lead to large hysteresis and device drifts, particularly when common amorphous gate oxides (such as silicon or hafnium dioxide) are used, hindering stable circuit operation. Here, we show that device stability in graphene-based field-effect transistors with amorphous gate oxides can be improved by Fermi-level tuning. We deliberately tune the Fermi level of the channel to maximize the energy distance between the charge carriers in the channel and the defect bands in the amorphous aluminium gate oxide. Charge trapping is highly sensitive to the energetic alignment of the Fermi level of the channel with the defect band in the insulator, and thus, our approach minimizes the amount of electrically active border traps without the need to reduce the total number of traps in the insulator.
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Affiliation(s)
| | - Burkay Uzlu
- AMO GmbH, Aachen, Germany
- Chair of Electronic Devices, RWTH Aachen University, Aachen, Germany
| | - Yury Yu. Illarionov
- Institute for Microelectronics, TU Wien, Vienna, Austria
- Ioffe Institute, Saint Petersburg, Russia
| | | | | | - Lado Filipovic
- Institute for Microelectronics, TU Wien, Vienna, Austria
| | - Michael Waltl
- Christian Doppler Laboratory for Single-Defect Spectroscopy in Semiconductor Devices at the Institute for Microelectronics, TU Wien, Vienna, Austria
| | - Daniel Neumaier
- AMO GmbH, Aachen, Germany
- Chair of Smart Sensor Systems, University of Wuppertal, Wuppertal, Germany
| | - Max C. Lemme
- AMO GmbH, Aachen, Germany
- Chair of Electronic Devices, RWTH Aachen University, Aachen, Germany
| | - Tibor Grasser
- Institute for Microelectronics, TU Wien, Vienna, Austria
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9
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Song Y, Wei X, Zhao Z, Yao Y, Bi L, Qiu Y, Long X, Chen Z, Wang S, Liao J. Plasma and magnetron sputtering constructed dual-functional polysulfides barrier separator for high-performance lithium-sulfur batteries. J Colloid Interface Sci 2022; 613:636-643. [PMID: 35065437 DOI: 10.1016/j.jcis.2022.01.077] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 01/05/2022] [Accepted: 01/11/2022] [Indexed: 12/01/2022]
Abstract
In order to fundamentally suppress the shuttle effect, N2 Plasma & Al2O3 magnetron sputtered separators (Al2O3@N-PP) are proposed for lithium-sulfur batteries (LSBs). Such a dual-functional polysulfides (LiPSs) barrier separator greatly inhibits the shuttle effect from the perspective of physical and chemical interaction. Physically, the inherently electronegative amorphous Al2O3 first achieves the repulsion of LiPSs to the sulfur cathode through the electrostatic repulsive effect, effectively preventing a large amount of soluble LiPSs from accumulating at the separator. At the same time, the Al2O3 film seals the shuttle channel of LiPSs to a certain extent. Chemically, N2 plasma-doped N heteroatoms form a lithium bond with Li+ in LiPSs to achieve the first step chemical adsorption and anchoring of LiPSs. When the LiPSs reaches the amorphous Al2O3 film, more stable chemical bonds are formed between Al3+ and S2-, Li+ and O2- to achieve more effective adsorption and anchoring of LiPSs. At 1C with a high sulfur loading up to 3-5 mg cm-2 the LSB contributes a specific charge capacity of 717.4 mAh g-1, with high retention rate up to 75.49 % after 450 cycles. The U-shaped electrolytic cell experiment and ultraviolet-visible spectrum experiment confirmed the LiPSs barrier function of the functional separator.
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Affiliation(s)
- Yaochen Song
- Yangtze Delta Region Institute (QuZhou), University of Electronic Science and Technology of China, 324000, PR China; School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, PR China
| | - Xiongbang Wei
- Yangtze Delta Region Institute (QuZhou), University of Electronic Science and Technology of China, 324000, PR China; School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, PR China
| | - Ziqi Zhao
- School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, PR China
| | - Yilin Yao
- School of Materials Science and Engineering, Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science & Technology, Xi'an 710021, PR China
| | - Linnan Bi
- Yangtze Delta Region Institute (QuZhou), University of Electronic Science and Technology of China, 324000, PR China; School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, PR China
| | - Yuhong Qiu
- Yangtze Delta Region Institute (QuZhou), University of Electronic Science and Technology of China, 324000, PR China; School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, PR China
| | - Xin Long
- Yangtze Delta Region Institute (QuZhou), University of Electronic Science and Technology of China, 324000, PR China; School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, PR China
| | - Zhi Chen
- Yangtze Delta Region Institute (QuZhou), University of Electronic Science and Technology of China, 324000, PR China; School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, PR China
| | - Sizhe Wang
- Yangtze Delta Region Institute (QuZhou), University of Electronic Science and Technology of China, 324000, PR China; School of Materials Science and Engineering, Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science & Technology, Xi'an 710021, PR China.
| | - Jiaxuan Liao
- Yangtze Delta Region Institute (QuZhou), University of Electronic Science and Technology of China, 324000, PR China; School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, PR China.
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10
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Lee JH, Kim DS, Kim JG, Ahn WH, Bae Y, Lee JH. Effect of gate dielectrics on characteristics of high-energy proton-irradiated AlGaN/GaN MISHEMTs. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2021.109473] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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Noircler G, Lebreton F, Drahi E, de Coux P, Warot-Fonrose B. STEM-EELS investigation of c-Si/a-AlO x interface for solar cell applications. Micron 2021; 145:103032. [PMID: 33735756 DOI: 10.1016/j.micron.2021.103032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/10/2021] [Accepted: 02/10/2021] [Indexed: 11/25/2022]
Abstract
In this article, STEM-EELS methodology is described to investigate the composition of sensitive crystalline Silicon/amorphous aluminum oxide (c-Si/a-AlOx) interface of an a AlOx/amorphous hydrogenated silicon nitride (a-AlOx/a-SiNx:H) passivation stack of a c-Si solar cell. In this stack, a-AlOx has the distinctive characteristic to provide both chemical and field effect passivation, which need further research to be more controlled in order to improve solar cell efficiency. a-AlOx is known to be unstable under the electron-beam, so we first present a detailed study on the electron-beam radiation damage to c-Si/a-AlOx interface. This interface can indeed undergo several electron-beam irradiation damage like sputtering, knock-on or radiolysis if precautions are not taken. Radiolysis damage has been found to be the dominant radiation damage. Thus, several STEM-EELS acquisition parameters like acceleration voltage, electron dose and scan orientation were taken into account and modified to limit this radiolysis damage. Once the irradiation was limited, STEM-EELS investigation was conduct using DualEELS on the Si and Al L2,3 and OK edge fines structures. The interface was found to be composed of a-SiOx and non-stoichiometric aluminum silicate with a predominance of tetrahedrally coordinated Al in its first layer.
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Affiliation(s)
- Guillaume Noircler
- Total S.A., 2 place Jean Millier, 92400 Paris La Défense, France; CEMES-CNRS, Université de Toulouse, CNRS, 29 rue Jeanne Marvig, 31055 Toulouse, France; Institut Photovoltaïque d'Ile-de-France (IPVF), 18, Boulevard Thomas Gobert, 91120 Palaiseau, France
| | - Fabien Lebreton
- Total S.A., 2 place Jean Millier, 92400 Paris La Défense, France; Institut Photovoltaïque d'Ile-de-France (IPVF), 18, Boulevard Thomas Gobert, 91120 Palaiseau, France; LPICM-CNRS - Ecole Polytechnique, 91128 Palaiseau, France
| | - Etienne Drahi
- Total S.A., 2 place Jean Millier, 92400 Paris La Défense, France; Institut Photovoltaïque d'Ile-de-France (IPVF), 18, Boulevard Thomas Gobert, 91120 Palaiseau, France
| | - Patricia de Coux
- Total S.A., 2 place Jean Millier, 92400 Paris La Défense, France
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12
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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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Pt-Amorphous Barium Aluminum Oxide/Carbon Catalysts for an Enhanced Methanol Electrooxidation Reaction. Catalysts 2020. [DOI: 10.3390/catal10060708] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
A new type of amorphous barium aluminum oxide was synthesized using a polyol thermal method involving a mixture with Vulcan XC-72 carbon and supported with 20%Pt catalysts to enhance the activity of a methanol electrooxidation reaction (MOR). The maximum current density, electrochemically active surface area (ECSA), and electrochemical impedance spectra (EIS) of the obtained catalysts for MOR were determined. The MORs of barium aluminum oxide with different calcination temperatures and Ba and Al contact ratios were studied. The MOR of the uncalcined amorphous Ba0.5AlOx catalysts prepared with a mole ratio of 2/1 Ba/Al mixed with Vulcan XC-72 carbon and supported with 20%Pt catalyst (Pt-Ba0.5AlOx/C) was enhanced compared with that of 20%Pt-Al2O3/C and 20%Pt/C catalysts due to its obtained largest maximum current density of 3.89 mA/cm2 and the largest ECSA of 49.83 m2/g. Therefore, Pt-Ba0.5AlOx/C could provide a new pathway to achieve a sufficient electrical conductivity, and possible synergistic effects with other active components improved the catalytic activity and stability of the prepared catalyst in MOR.
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Leonhardt A, Chiappe D, Afanas'ev VV, El Kazzi S, Shlyakhov I, Conard T, Franquet A, Huyghebaert C, de Gendt S. Material-Selective Doping of 2D TMDC through Al xO y Encapsulation. ACS APPLIED MATERIALS & INTERFACES 2019; 11:42697-42707. [PMID: 31625717 DOI: 10.1021/acsami.9b11550] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
For the integration of two-dimensional (2D) transition metal dichalcogenides (TMDC) with high-performance electronic systems, one of the greatest challenges is the realization of doping and comprehension of its mechanisms. Low-temperature atomic layer deposition of aluminum oxide is found to n-dope MoS2 and ReS2 but not WS2. Based on electrical, optical, and chemical analyses, we propose and validate a hypothesis to explain the doping mechanism. Doping is ascribed to donor states in the band gap of AlxOy, which donate electrons or not, based on the alignment of the electronic bands of the 2D TMDC. Through systematic experimental characterization, incorporation of impurities (e.g., carbon) is identified as the likely cause of such states. By modulating the carbon concentration in the capping oxide, doping can be controlled. Through systematic and comprehensive experimental analysis, this study correlates, for the first time, 2D TMDC doping to the carbon incorporation on dielectric encapsulation layers. We highlight the possibility to engineer dopant layers to control the material selectivity and doping concentration in 2D TMDC.
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Affiliation(s)
- Alessandra Leonhardt
- Department of Chemistry , K.U. Leuven , Celestijnenlaan 200 F , B-3001 Leuven , Belgium
- Imec , Kapeldreef 75 , 3001 Leuven , Belgium
| | | | - Valeri V Afanas'ev
- Department of Physics and Astronomy , K.U. Leuven , Celestijnenlaan 200 D , B-3001 Leuven , Belgium
| | | | - Ilya Shlyakhov
- Department of Physics and Astronomy , K.U. Leuven , Celestijnenlaan 200 D , B-3001 Leuven , Belgium
| | | | | | | | - Stefan de Gendt
- Department of Chemistry , K.U. Leuven , Celestijnenlaan 200 F , B-3001 Leuven , Belgium
- Imec , Kapeldreef 75 , 3001 Leuven , Belgium
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