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Origin of Weaker Fermi Level Pinning and Localized Interface States at Metal Silicide Schottky Barriers

Zhaofu Zhang, Yuzheng Guo Orcid Logo, John Robertson

The Journal of Physical Chemistry C, Volume: 124, Issue: 36, Pages: 19698 - 19703

Swansea University Author: Yuzheng Guo Orcid Logo

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DOI (Published version): 10.1021/acs.jpcc.0c06228

Abstract

The Schottky barriers of transition metal silicides on silicon are characterized by two anomalous features, a face dependence of Schottky barrier heights (SBHs) and a weaker than expected dependence of SBHs on work function or “weaker Fermi level pinning.” Density functional supercell calculations r...

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Published in: The Journal of Physical Chemistry C
ISSN: 1932-7447 1932-7455
Published: American Chemical Society (ACS) 2020
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URI: https://cronfa.swan.ac.uk/Record/cronfa55624
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spelling 2020-12-29T15:11:50.6341834 v2 55624 2020-11-09 Origin of Weaker Fermi Level Pinning and Localized Interface States at Metal Silicide Schottky Barriers 2c285ab01f88f7ecb25a3aacabee52ea 0000-0003-2656-0340 Yuzheng Guo Yuzheng Guo true false 2020-11-09 GENG The Schottky barriers of transition metal silicides on silicon are characterized by two anomalous features, a face dependence of Schottky barrier heights (SBHs) and a weaker than expected dependence of SBHs on work function or “weaker Fermi level pinning.” Density functional supercell calculations reported here find that these features arise from the occurrence of localized gap states at interfacial coordination defects, in addition to the usual metal-induced gap states (MIGSs), and these lead to pinning energies that increase sequentially across the Si gap from PtSi2 to YbSi2. The interfacial gap states vary in shape with face orientation and cause the unusual face-dependent SBHs. The localized interface defect states are a key missing addition to the MIGS model, which are needed to describe fully the interface bonding such as face orientation or coordination defects. This anomalous Fermi level pinning does not reduce gap state densities but could be used to better control SBHs by creating specific configurations with near band edge pinning energies, thus giving low contact resistances in highly scaled silicon devices or 2D semiconductors. Journal Article The Journal of Physical Chemistry C 124 36 19698 19703 American Chemical Society (ACS) 1932-7447 1932-7455 Schottky barrier, Fermi level depinning, metal silicide, semiconductor contacts 10 9 2020 2020-09-10 10.1021/acs.jpcc.0c06228 COLLEGE NANME General Engineering COLLEGE CODE GENG Swansea University 2020-12-29T15:11:50.6341834 2020-11-09T09:33:05.9500367 Faculty of Science and Engineering School of Aerospace, Civil, Electrical, General and Mechanical Engineering - General Engineering Zhaofu Zhang 1 Yuzheng Guo 0000-0003-2656-0340 2 John Robertson 3 55624__18626__b6ade84bcbc148b6a443edb6fbeba5d0.pdf 55624.pdf 2020-11-10T11:08:57.9076475 Output 995007 application/pdf Accepted Manuscript true 2021-08-11T00:00:00.0000000 true eng
title Origin of Weaker Fermi Level Pinning and Localized Interface States at Metal Silicide Schottky Barriers
spellingShingle Origin of Weaker Fermi Level Pinning and Localized Interface States at Metal Silicide Schottky Barriers
Yuzheng Guo
title_short Origin of Weaker Fermi Level Pinning and Localized Interface States at Metal Silicide Schottky Barriers
title_full Origin of Weaker Fermi Level Pinning and Localized Interface States at Metal Silicide Schottky Barriers
title_fullStr Origin of Weaker Fermi Level Pinning and Localized Interface States at Metal Silicide Schottky Barriers
title_full_unstemmed Origin of Weaker Fermi Level Pinning and Localized Interface States at Metal Silicide Schottky Barriers
title_sort Origin of Weaker Fermi Level Pinning and Localized Interface States at Metal Silicide Schottky Barriers
author_id_str_mv 2c285ab01f88f7ecb25a3aacabee52ea
author_id_fullname_str_mv 2c285ab01f88f7ecb25a3aacabee52ea_***_Yuzheng Guo
author Yuzheng Guo
author2 Zhaofu Zhang
Yuzheng Guo
John Robertson
format Journal article
container_title The Journal of Physical Chemistry C
container_volume 124
container_issue 36
container_start_page 19698
publishDate 2020
institution Swansea University
issn 1932-7447
1932-7455
doi_str_mv 10.1021/acs.jpcc.0c06228
publisher American Chemical Society (ACS)
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Aerospace, Civil, Electrical, General and Mechanical Engineering - General Engineering{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Aerospace, Civil, Electrical, General and Mechanical Engineering - General Engineering
document_store_str 1
active_str 0
description The Schottky barriers of transition metal silicides on silicon are characterized by two anomalous features, a face dependence of Schottky barrier heights (SBHs) and a weaker than expected dependence of SBHs on work function or “weaker Fermi level pinning.” Density functional supercell calculations reported here find that these features arise from the occurrence of localized gap states at interfacial coordination defects, in addition to the usual metal-induced gap states (MIGSs), and these lead to pinning energies that increase sequentially across the Si gap from PtSi2 to YbSi2. The interfacial gap states vary in shape with face orientation and cause the unusual face-dependent SBHs. The localized interface defect states are a key missing addition to the MIGS model, which are needed to describe fully the interface bonding such as face orientation or coordination defects. This anomalous Fermi level pinning does not reduce gap state densities but could be used to better control SBHs by creating specific configurations with near band edge pinning energies, thus giving low contact resistances in highly scaled silicon devices or 2D semiconductors.
published_date 2020-09-10T04:09:58Z
_version_ 1763753694606655488
score 11.036706

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