Schottky Contacts on Polarity-Controlled Vertical ZnO Nanorods

Lord, Alex; Consonni, Vincent; Cossuet, Thomas; Donatini, Fabrice; Wilks, Steve

doi:10.1021/acsami.9b23260

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Schottky Contacts on Polarity-Controlled Vertical ZnO Nanorods

Alex Lord

, Vincent Consonni, Thomas Cossuet, Fabrice Donatini, Steve Wilks

ACS Applied Materials & Interfaces, Volume: 12, Issue: 11, Pages: 13217 - 13228

Swansea University Authors: Alex Lord , Steve Wilks

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DOI (Published version): 10.1021/acsami.9b23260

Abstract

Polarity-controlled growth of ZnO by chemical bath deposition provides a method for controlling the crystal orientation of vertical arrays of nanorods. The ability to define the morphology and structure of the nanorods is essential to maximising the performance of optical and electrical devices such...

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Published in:	ACS Applied Materials & Interfaces
ISSN:	1944-8244 1944-8252
Published:	American Chemical Society (ACS) 2020
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URI:	https://cronfa.swan.ac.uk/Record/cronfa53637
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spelling	2020-08-17T14:09:56.4712606 v2 53637 2020-02-25 Schottky Contacts on Polarity-Controlled Vertical ZnO Nanorods d547bad707e12f5a9f12d4fcbeea87ed 0000-0002-6258-2187 Alex Lord Alex Lord true false 948a547e27d969b7e192b4620688704d Steve Wilks Steve Wilks true false 2020-02-25 EEN Polarity-controlled growth of ZnO by chemical bath deposition provides a method for controlling the crystal orientation of vertical arrays of nanorods. The ability to define the morphology and structure of the nanorods is essential to maximising the performance of optical and electrical devices such as piezoelectric nanogenerators; however, well-defined Schottky contacts to the polar facets of the structures have yet to be explored. In this work, we demonstrate a process to fabricate metal-semiconductor-metal device structures from vertical arrays with Au contacts on the uppermost polar facets of the nanorods and show the O-polar nanorods (~0.44 eV) have a greater effective barrier height than the Zn-polar nanorods (~0.37 eV). Oxygen plasma treatment is shown by Cathodoluminescence (CL) spectroscopy to reduce mid-gap defects associated with radiative emissions that improves the Schottky contacts from weakly-rectifying to strongly-rectifying. Interestingly, the plasma treatment was shown to have a much greater effect in reducing the number of carriers in O-polar nanorods through quenching of the donor-type substitutional hydrogen on oxygen sites (HO) when compared to the zinc vacancy related hydrogen defect complexes (VZn, Hn) in Zn-polar nanorods that evolve to lower coordinated complexes. The effect on HO in the O-polar nanorods coincided with a large reduction in the visible range defects producing a lower conductivity and creating the larger effective barrier heights. This combination can allow radiative losses and charge leakage to be controlled enhancing devices such as dynamic photodetectors, strain sensors, and LEDs while showing the O-polar nanorods can outperform Zn-polar nanorods in such applications. Journal Article ACS Applied Materials & Interfaces 12 11 13217 13228 American Chemical Society (ACS) 1944-8244 1944-8252 ZnO, Nanorods, Polarity, Schottky Contacts, Electrical Transport, Cathodoluminescence, Defects 18 3 2020 2020-03-18 10.1021/acsami.9b23260 COLLEGE NANME Engineering COLLEGE CODE EEN Swansea University UKRI, EP/R511614/1 2020-08-17T14:09:56.4712606 2020-02-25T14:55:30.9206066 Alex Lord 0000-0002-6258-2187 1 Vincent Consonni 2 Thomas Cossuet 3 Fabrice Donatini 4 Steve Wilks 5 53637__16988__d7d1731a09414cf092517bf97bf14019.pdf 53637.pdf 2020-04-02T09:19:46.5332077 Output 2651145 application/pdf Version of Record true Released under the terms of a Creative Commons Attribution License (CC-BY). true eng http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html
title	Schottky Contacts on Polarity-Controlled Vertical ZnO Nanorods
spellingShingle	Schottky Contacts on Polarity-Controlled Vertical ZnO Nanorods Alex Lord Steve Wilks
title_short	Schottky Contacts on Polarity-Controlled Vertical ZnO Nanorods
title_full	Schottky Contacts on Polarity-Controlled Vertical ZnO Nanorods
title_fullStr	Schottky Contacts on Polarity-Controlled Vertical ZnO Nanorods
title_full_unstemmed	Schottky Contacts on Polarity-Controlled Vertical ZnO Nanorods
title_sort	Schottky Contacts on Polarity-Controlled Vertical ZnO Nanorods
author_id_str_mv	d547bad707e12f5a9f12d4fcbeea87ed 948a547e27d969b7e192b4620688704d
author_id_fullname_str_mv	d547bad707e12f5a9f12d4fcbeea87ed_*_Alex Lord 948a547e27d969b7e192b4620688704d_*_Steve Wilks
author	Alex Lord Steve Wilks
author2	Alex Lord Vincent Consonni Thomas Cossuet Fabrice Donatini Steve Wilks
format	Journal article
container_title	ACS Applied Materials & Interfaces
container_volume	12
container_issue	11
container_start_page	13217
publishDate	2020
institution	Swansea University
issn	1944-8244 1944-8252
doi_str_mv	10.1021/acsami.9b23260
publisher	American Chemical Society (ACS)
document_store_str	1
active_str	0
description	Polarity-controlled growth of ZnO by chemical bath deposition provides a method for controlling the crystal orientation of vertical arrays of nanorods. The ability to define the morphology and structure of the nanorods is essential to maximising the performance of optical and electrical devices such as piezoelectric nanogenerators; however, well-defined Schottky contacts to the polar facets of the structures have yet to be explored. In this work, we demonstrate a process to fabricate metal-semiconductor-metal device structures from vertical arrays with Au contacts on the uppermost polar facets of the nanorods and show the O-polar nanorods (~0.44 eV) have a greater effective barrier height than the Zn-polar nanorods (~0.37 eV). Oxygen plasma treatment is shown by Cathodoluminescence (CL) spectroscopy to reduce mid-gap defects associated with radiative emissions that improves the Schottky contacts from weakly-rectifying to strongly-rectifying. Interestingly, the plasma treatment was shown to have a much greater effect in reducing the number of carriers in O-polar nanorods through quenching of the donor-type substitutional hydrogen on oxygen sites (HO) when compared to the zinc vacancy related hydrogen defect complexes (VZn, Hn) in Zn-polar nanorods that evolve to lower coordinated complexes. The effect on HO in the O-polar nanorods coincided with a large reduction in the visible range defects producing a lower conductivity and creating the larger effective barrier heights. This combination can allow radiative losses and charge leakage to be controlled enhancing devices such as dynamic photodetectors, strain sensors, and LEDs while showing the O-polar nanorods can outperform Zn-polar nanorods in such applications.
published_date	2020-03-18T04:06:42Z
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score	11.013148

Schottky Contacts on Polarity-Controlled Vertical ZnO Nanorods

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