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DFT/NEGF study of discrete dopants in Si/III–V 3D FET

L S J Wilson, J R Barker, A E Martinez, Antonio Martinez Muniz Orcid Logo

Journal of Physics: Condensed Matter, Volume: 31, Issue: 14, Start page: 144003

Swansea University Author: Antonio Martinez Muniz Orcid Logo

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Abstract

In this work, electron densities around dopants in Si and GaAs have been calculated using density functional theory (DFT) calculations. These extracted densities have been used to describe dopants in an in-house non-equilibrium Green functions device simulator. The transfer characteristics of nanowi...

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Published in: Journal of Physics: Condensed Matter
ISSN: 0953-8984 1361-648X
Published: 2019
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URI: https://cronfa.swan.ac.uk/Record/cronfa49102
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spelling 2019-06-06T15:57:17.3499528 v2 49102 2019-03-04 DFT/NEGF study of discrete dopants in Si/III–V 3D FET cd433784251add853672979313f838ec 0000-0001-8131-7242 Antonio Martinez Muniz Antonio Martinez Muniz true false 2019-03-04 EEEG In this work, electron densities around dopants in Si and GaAs have been calculated using density functional theory (DFT) calculations. These extracted densities have been used to describe dopants in an in-house non-equilibrium Green functions device simulator. The transfer characteristics of nanowire gate all around field effect transistor have been calculated using DFT electron densities. These transport calculations were compared with those using a point charge model of the dopant. The dopants are located in the middle of the channel of the device. Specifically, DFT calculations of a 512 atom Si supercell with a single impurity atom have been carried out, both phosphorous and boron atoms have been used as donor and acceptor impurities respectively. The calculations were repeated on a gallium arsenide supercell, where the silicon atom substituted gallium and arsenide to act as donor and acceptor respectively. We found that for donors and acceptors, the DFT charge distribution extends similarly in both materials. In addition, the relaxed structure produces a 50% larger spread of electronic charge as compared with unrelaxed Si and GaAs. The extracted current voltage characteristics of the devices are altered significantly using the charge density obtained by DFT. At 0.7 V the current in Si is 20% larger using the DFT charge density compared to the point charge model for donors. Whereas the current using the point charge model in GaAs is 2.5 times larger than the distributed charge. Devices exhibit substantial tunnelling currents for donors and acceptors irrespective of the model of the dopant considered. In GaAs, this was 76% using a point charge and 78% using the distributed charge when using a donor; 61% and 68% in Si respectively. The tunnelling current using acceptors for Si was 100% and 99% using GaAs for both models. Journal Article Journal of Physics: Condensed Matter 31 14 144003 0953-8984 1361-648X 31 12 2019 2019-12-31 10.1088/1361-648X/aaffb2 COLLEGE NANME Electronic and Electrical Engineering COLLEGE CODE EEEG Swansea University 2019-06-06T15:57:17.3499528 2019-03-04T09:42:45.2167939 College of Engineering Engineering L S J Wilson 1 J R Barker 2 A E Martinez 3 Antonio Martinez Muniz 0000-0001-8131-7242 4
title DFT/NEGF study of discrete dopants in Si/III–V 3D FET
spellingShingle DFT/NEGF study of discrete dopants in Si/III–V 3D FET
Antonio Martinez Muniz
title_short DFT/NEGF study of discrete dopants in Si/III–V 3D FET
title_full DFT/NEGF study of discrete dopants in Si/III–V 3D FET
title_fullStr DFT/NEGF study of discrete dopants in Si/III–V 3D FET
title_full_unstemmed DFT/NEGF study of discrete dopants in Si/III–V 3D FET
title_sort DFT/NEGF study of discrete dopants in Si/III–V 3D FET
author_id_str_mv cd433784251add853672979313f838ec
author_id_fullname_str_mv cd433784251add853672979313f838ec_***_Antonio Martinez Muniz
author Antonio Martinez Muniz
author2 L S J Wilson
J R Barker
A E Martinez
Antonio Martinez Muniz
format Journal article
container_title Journal of Physics: Condensed Matter
container_volume 31
container_issue 14
container_start_page 144003
publishDate 2019
institution Swansea University
issn 0953-8984
1361-648X
doi_str_mv 10.1088/1361-648X/aaffb2
college_str College of Engineering
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hierarchy_top_id collegeofengineering
hierarchy_top_title College of Engineering
hierarchy_parent_id collegeofengineering
hierarchy_parent_title College of Engineering
department_str Engineering{{{_:::_}}}College of Engineering{{{_:::_}}}Engineering
document_store_str 0
active_str 0
description In this work, electron densities around dopants in Si and GaAs have been calculated using density functional theory (DFT) calculations. These extracted densities have been used to describe dopants in an in-house non-equilibrium Green functions device simulator. The transfer characteristics of nanowire gate all around field effect transistor have been calculated using DFT electron densities. These transport calculations were compared with those using a point charge model of the dopant. The dopants are located in the middle of the channel of the device. Specifically, DFT calculations of a 512 atom Si supercell with a single impurity atom have been carried out, both phosphorous and boron atoms have been used as donor and acceptor impurities respectively. The calculations were repeated on a gallium arsenide supercell, where the silicon atom substituted gallium and arsenide to act as donor and acceptor respectively. We found that for donors and acceptors, the DFT charge distribution extends similarly in both materials. In addition, the relaxed structure produces a 50% larger spread of electronic charge as compared with unrelaxed Si and GaAs. The extracted current voltage characteristics of the devices are altered significantly using the charge density obtained by DFT. At 0.7 V the current in Si is 20% larger using the DFT charge density compared to the point charge model for donors. Whereas the current using the point charge model in GaAs is 2.5 times larger than the distributed charge. Devices exhibit substantial tunnelling currents for donors and acceptors irrespective of the model of the dopant considered. In GaAs, this was 76% using a point charge and 78% using the distributed charge when using a donor; 61% and 68% in Si respectively. The tunnelling current using acceptors for Si was 100% and 99% using GaAs for both models.
published_date 2019-12-31T04:02:04Z
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score 10.896665