Fermi level depinning via insertion of a graphene buffer layer at the gold-2D tin monoxide contact

Two-dimensional (2D) tin monoxide (SnO) has attracted much attention owing to its distinctive electronic and optical properties, which render itself suitable as a channel material in field effect transistors (FETs). However, upon contact with metals for such applications, the Fermi level pinning eff...

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Main Authors: Tian, Yujia, Kripalani, Devesh R., Xue, Ming, Zhou, Kun
Other Authors: School of Mechanical and Aerospace Engineering
Format: Article
Language:English
Published: 2023
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Online Access:https://hdl.handle.net/10356/171331
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1713312023-10-23T05:12:51Z Fermi level depinning via insertion of a graphene buffer layer at the gold-2D tin monoxide contact Tian, Yujia Kripalani, Devesh R. Xue, Ming Zhou, Kun School of Mechanical and Aerospace Engineering Engineering::Mechanical engineering Heterojunctions Metal-Semiconductor Contacts Two-dimensional (2D) tin monoxide (SnO) has attracted much attention owing to its distinctive electronic and optical properties, which render itself suitable as a channel material in field effect transistors (FETs). However, upon contact with metals for such applications, the Fermi level pinning effect may occur, where states are induced in its band gap by the metal, hindering its intrinsic semiconducting properties. We propose the insertion of graphene at the contact interface to alleviate the metal-induced gap states. By using gold (Au) as the electrode material and monolayer SnO (mSnO) as the channel material, the geometry, bonding strength, charge transfer and tunnel barriers of charges, and electronic properties including the work function, band structure, density of states, and Schottky barriers are thoroughly investigated using first-principles calculations for the structures with and without graphene to reveal the contact behaviours and Fermi level depinning mechanism. It has been demonstrated that strong covalent bonding is formed between gold and mSnO, while the graphene interlayer forms weak van der Waals interaction with both materials, which minimises the perturbance to the band structure of mSnO. The effects of out-of-plane compression are also analysed to assess the performance of the contact under mechanical deformation, and a feasible fabrication route for the heterostructure with graphene is proposed. This work systematically explores the properties of the Au-mSnO contact for applications in FETs and provides thorough guidance for future exploitation of 2D materials in various electronic applications and for selection of buffer layers to improve metal-semiconductor contact. Economic Development Board (EDB) This study was supported by the Economic Development Board - Singapore and Infineon Technologies Asia Pacific Pte. Ltd. through the Industrial Postgraduate Programme with Nanyang Technological University (NTU). The computational calculations for this study were partially conducted using the resources of the National Supercomputing Centre, Singapore and High Performance Computing Centre, NTU. 2023-10-23T05:12:51Z 2023-10-23T05:12:51Z 2023 Journal Article Tian, Y., Kripalani, D. R., Xue, M. & Zhou, K. (2023). Fermi level depinning via insertion of a graphene buffer layer at the gold-2D tin monoxide contact. 2D Materials, 10(4), 045015-. https://dx.doi.org/10.1088/2053-1583/aceb05 2053-1583 https://hdl.handle.net/10356/171331 10.1088/2053-1583/aceb05 2-s2.0-85169886102 4 10 045015 en 2D Materials © 2023 IOP Publishing Ltd. All rights reserved.
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Mechanical engineering
Heterojunctions
Metal-Semiconductor Contacts
spellingShingle Engineering::Mechanical engineering
Heterojunctions
Metal-Semiconductor Contacts
Tian, Yujia
Kripalani, Devesh R.
Xue, Ming
Zhou, Kun
Fermi level depinning via insertion of a graphene buffer layer at the gold-2D tin monoxide contact
description Two-dimensional (2D) tin monoxide (SnO) has attracted much attention owing to its distinctive electronic and optical properties, which render itself suitable as a channel material in field effect transistors (FETs). However, upon contact with metals for such applications, the Fermi level pinning effect may occur, where states are induced in its band gap by the metal, hindering its intrinsic semiconducting properties. We propose the insertion of graphene at the contact interface to alleviate the metal-induced gap states. By using gold (Au) as the electrode material and monolayer SnO (mSnO) as the channel material, the geometry, bonding strength, charge transfer and tunnel barriers of charges, and electronic properties including the work function, band structure, density of states, and Schottky barriers are thoroughly investigated using first-principles calculations for the structures with and without graphene to reveal the contact behaviours and Fermi level depinning mechanism. It has been demonstrated that strong covalent bonding is formed between gold and mSnO, while the graphene interlayer forms weak van der Waals interaction with both materials, which minimises the perturbance to the band structure of mSnO. The effects of out-of-plane compression are also analysed to assess the performance of the contact under mechanical deformation, and a feasible fabrication route for the heterostructure with graphene is proposed. This work systematically explores the properties of the Au-mSnO contact for applications in FETs and provides thorough guidance for future exploitation of 2D materials in various electronic applications and for selection of buffer layers to improve metal-semiconductor contact.
author2 School of Mechanical and Aerospace Engineering
author_facet School of Mechanical and Aerospace Engineering
Tian, Yujia
Kripalani, Devesh R.
Xue, Ming
Zhou, Kun
format Article
author Tian, Yujia
Kripalani, Devesh R.
Xue, Ming
Zhou, Kun
author_sort Tian, Yujia
title Fermi level depinning via insertion of a graphene buffer layer at the gold-2D tin monoxide contact
title_short Fermi level depinning via insertion of a graphene buffer layer at the gold-2D tin monoxide contact
title_full Fermi level depinning via insertion of a graphene buffer layer at the gold-2D tin monoxide contact
title_fullStr Fermi level depinning via insertion of a graphene buffer layer at the gold-2D tin monoxide contact
title_full_unstemmed Fermi level depinning via insertion of a graphene buffer layer at the gold-2D tin monoxide contact
title_sort fermi level depinning via insertion of a graphene buffer layer at the gold-2d tin monoxide contact
publishDate 2023
url https://hdl.handle.net/10356/171331
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