Photoinduced oxygen release and persistent photoconductivity in ZnO nanowires
Open Access
- 31 May 2011
- journal article
- research article
- Published by Springer Science and Business Media LLC in Nanoscale Research Letters
- Vol. 6 (1), 404
- https://doi.org/10.1186/1556-276x-6-404
Abstract
Photoconductivity is studied in individual ZnO nanowires. Under ultraviolet (UV) illumination, the induced photocurrents are observed to persist both in air and in vacuum. Their dependence on UV intensity in air is explained by means of photoinduced surface depletion depth decrease caused by oxygen desorption induced by photogenerated holes. The observed photoresponse is much greater in vacuum and proceeds beyond the air photoresponse at a much slower rate of increase. After reaching a maximum, it typically persists indefinitely, as long as good vacuum is maintained. Once vacuum is broken and air is let in, the photocurrent quickly decays down to the typical air-photoresponse values. The extra photoconductivity in vacuum is explained by desorption of adsorbed surface oxygen which is readily pumped out, followed by a further slower desorption of lattice oxygen, resulting in a Zn-rich surface of increased conductivity. The adsorption-desorption balance is fully recovered after the ZnO surface is exposed to air, which suggests that under UV illumination, the ZnO surface is actively "breathing" oxygen, a process that is further enhanced in nanowires by their high surface to volume ratio.Keywords
This publication has 34 references indexed in Scilit:
- Broadband ZnO Single-Nanowire Light-Emitting DiodeNano Letters, 2006
- Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire ArraysScience, 2006
- Oxygen vacancies in ZnOApplied Physics Letters, 2005
- Enhanced Field Emission of ZnO NanowiresAdvanced Materials, 2004
- Integrated nanoscale electronics and optoelectronics: Exploring nanoscale science and technology through semiconductor nanowiresPure and Applied Chemistry, 2004
- Nanoscale Science and Technology: Building a Big Future from Small ThingsMRS Bulletin, 2003
- Photochemistry of colloidal semiconductors. 31. Preparation and photolysis of cadmium sulfide sols in organic solventsThe Journal of Physical Chemistry, 1989
- Zinc oxide: an outstanding example of a binary compound semiconductorAccounts of Chemical Research, 1985
- Photo-assisted surface reactions studied by dynamic mass spectrometryFaraday Discussions of the Chemical Society, 1974
- Photoconduction and Surface Effects with Zinc Oxide CrystalsPhysical Review B, 1958