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XPS investigation of titanium contact formation to ZnO nanowires

Chris J Barnett, Ambroise Castaing, Daniel R Jones, Aled R Lewis, Lewys J Jenkins, Richard Cobley Orcid Logo, Thierry Maffeis Orcid Logo

Nanotechnology, Volume: 28, Issue: 8, Start page: 085301

Swansea University Authors: Richard Cobley Orcid Logo, Thierry Maffeis Orcid Logo

Abstract

Ti is often used to form an initial Ohmic interface between ZnO and Au due to its low work function, and the TiO2/ZnO heterojunction is also of great importance for many practical applications of nanoparticles. Here, Ti has been controllably deposited onto hydrothermally grown ZnO nanowires and the...

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Published in: Nanotechnology
ISSN: 0957-4484 1361-6528
Published: 2017
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URI: https://cronfa.swan.ac.uk/Record/cronfa31988
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spelling 2020-06-24T13:46:35.1872930 v2 31988 2017-02-15 XPS investigation of titanium contact formation to ZnO nanowires 2ce7e1dd9006164425415a35fa452494 0000-0003-4833-8492 Richard Cobley Richard Cobley true false 992eb4cb18b61c0cd3da6e0215ac787c 0000-0003-2357-0092 Thierry Maffeis Thierry Maffeis true false 2017-02-15 EEEG Ti is often used to form an initial Ohmic interface between ZnO and Au due to its low work function, and the TiO2/ZnO heterojunction is also of great importance for many practical applications of nanoparticles. Here, Ti has been controllably deposited onto hydrothermally grown ZnO nanowires and the formation of metal–semiconductor contact has been investigated using x-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and scanning electron microscopy. XPS results showed that that the Ti initially reacts with surface oxygen species to form TiO2, and further deposition results in the formation of oxides with oxidation state numbers lower than four, and eventually metallic Ti on top of the TiO2. The formation of TiC was also observed. XPS showed that the onset of metallic Ti coincided with a Zn 3p core level shift to lower binding energy, indicating upwards band bending and the formation of a rectifying contact. Annealing caused a near-complete conversion of the metallic Ti to TiO2 and caused the Zn 3p to shift back to its original higher binding energy, resulting in downwards band bending and a more Ohmic contact. PL measurements showed that the optical properties of the nanowires are not affected by the contact formation. Journal Article Nanotechnology 28 8 085301 0957-4484 1361-6528 contact; nanowires; Ohmic; Schottky; titanium; XPS; ZnO 19 1 2017 2017-01-19 10.1088/1361-6528/aa5663 COLLEGE NANME Electronic and Electrical Engineering COLLEGE CODE EEEG Swansea University 2020-06-24T13:46:35.1872930 2017-02-15T11:18:02.2575809 Faculty of Science and Engineering School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Electronic and Electrical Engineering Chris J Barnett 1 Ambroise Castaing 2 Daniel R Jones 3 Aled R Lewis 4 Lewys J Jenkins 5 Richard Cobley 0000-0003-4833-8492 6 Thierry Maffeis 0000-0003-2357-0092 7 0031988-16022017104433.pdf barnett2017.pdf 2017-02-16T10:44:33.0230000 Output 1568104 application/pdf Accepted Manuscript true 2018-01-19T00:00:00.0000000 true eng
title XPS investigation of titanium contact formation to ZnO nanowires
spellingShingle XPS investigation of titanium contact formation to ZnO nanowires
Richard Cobley
Thierry Maffeis
title_short XPS investigation of titanium contact formation to ZnO nanowires
title_full XPS investigation of titanium contact formation to ZnO nanowires
title_fullStr XPS investigation of titanium contact formation to ZnO nanowires
title_full_unstemmed XPS investigation of titanium contact formation to ZnO nanowires
title_sort XPS investigation of titanium contact formation to ZnO nanowires
author_id_str_mv 2ce7e1dd9006164425415a35fa452494
992eb4cb18b61c0cd3da6e0215ac787c
author_id_fullname_str_mv 2ce7e1dd9006164425415a35fa452494_***_Richard Cobley
992eb4cb18b61c0cd3da6e0215ac787c_***_Thierry Maffeis
author Richard Cobley
Thierry Maffeis
author2 Chris J Barnett
Ambroise Castaing
Daniel R Jones
Aled R Lewis
Lewys J Jenkins
Richard Cobley
Thierry Maffeis
format Journal article
container_title Nanotechnology
container_volume 28
container_issue 8
container_start_page 085301
publishDate 2017
institution Swansea University
issn 0957-4484
1361-6528
doi_str_mv 10.1088/1361-6528/aa5663
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 - Electronic and Electrical Engineering{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Electronic and Electrical Engineering
document_store_str 1
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description Ti is often used to form an initial Ohmic interface between ZnO and Au due to its low work function, and the TiO2/ZnO heterojunction is also of great importance for many practical applications of nanoparticles. Here, Ti has been controllably deposited onto hydrothermally grown ZnO nanowires and the formation of metal–semiconductor contact has been investigated using x-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and scanning electron microscopy. XPS results showed that that the Ti initially reacts with surface oxygen species to form TiO2, and further deposition results in the formation of oxides with oxidation state numbers lower than four, and eventually metallic Ti on top of the TiO2. The formation of TiC was also observed. XPS showed that the onset of metallic Ti coincided with a Zn 3p core level shift to lower binding energy, indicating upwards band bending and the formation of a rectifying contact. Annealing caused a near-complete conversion of the metallic Ti to TiO2 and caused the Zn 3p to shift back to its original higher binding energy, resulting in downwards band bending and a more Ohmic contact. PL measurements showed that the optical properties of the nanowires are not affected by the contact formation.
published_date 2017-01-19T03:39:07Z
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