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Schottky Contacts on Polarity-Controlled Vertical ZnO Nanorods
,
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...
| Published in: | ACS Applied Materials & Interfaces |
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| ISSN: | 1944-8244 1944-8252 |
| Published: |
American Chemical Society (ACS)
2020
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa53637 |
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| 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 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. |
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| Keywords: |
ZnO, Nanorods, Polarity, Schottky Contacts, Electrical Transport, Cathodoluminescence, Defects |
| Funders: |
UKRI, EP/R511614/1 |
| Issue: |
11 |
| Start Page: |
13217 |
| End Page: |
13228 |