Open Access Nano Express

Persistent Photoconductivity Studies in Nanostructured ZnO UV Sensors

Shiva Hullavarad1*, Nilima Hullavarad1, David Look2 and Bruce Claflin2

Author Affiliations

1 Office of Electronic Miniaturization, University of Alaska, Fairbanks, AK, 99701, USA

2 Semiconductor Research Center, Wright State University, Dayton, OH, 45435, USA

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Nanoscale Research Letters 2009, 4:1421-1427  doi:10.1007/s11671-009-9414-7

Published: 28 August 2009

Abstract

The phenomenon of persistent photoconductivity is elusive and has not been addressed to an extent to attract attention both in micro and nanoscale devices due to unavailability of clear material systems and device configurations capable of providing comprehensive information. In this work, we have employed a nanostructured (nanowire diameter 30–65 nm and 5 μm in length) ZnO-based metal–semiconductor–metal photoconductor device in order to study the origin of persistent photoconductivity. The current–voltage measurements were carried with and without UV illumination under different oxygen levels. The photoresponse measurements indicated a persistent conductivity trend for depleted oxygen conditions. The persistent conductivity phenomenon is explained on the theoretical model that proposes the change of a neutral anion vacancy to a charged state.

Keywords:
Persistent photoconductivity; Semiconducting II–VI materials; Zinc oxide; UV sensor; Nanoscale device