2008 NSTI Nanotechnology Conference and Trade Show - Nanotech 2008 - 11th Annual

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TechConnect Summit
Clean Technology 2008

Persistent Photo-conductivity in nanostructured ZnO UV detector

S.S. Hullavarad, N.V. Hullavarad
University of Alaska Fairbanks, US

Keywords:
ZnO, nanostructure, UV detector

Abstract:
The miniaturization of future electronic platforms demands the high density integration in order to achieve high speed, low power consumption and less space. This endeavor demands a new outlook in realizing the devices by employing the techniques of nanoscale electronics at the basic atom or cluster of atoms scale as building blocks. There is a great deal of interest in the development of optical semiconductor nanowires, because the quantized dimensions and geometrical shapes lead to strong confinement of electrons, and holes that have potential applications in nanoscale electronics and optoelectronic devices such as quantum efficient lasers and non-linear optical converters. ZnO has been widely reported as a visible blind UV detector over a wide range of applications in military and non-military arenas that includes missile plume detection for hostile missile tracking, flame sensors, UV source monitoring, and calibration. The research in the sensor area has lead many researchers to explore the possibility of widening the band gap of ZnO by alloying with Cd and Mg so as to cover UV-A, UV-B and UV-C region of ultra violet region. The present work describes the persistent photoconductivity in UV detector fabricated from nanostructured ZnO. ZnO nanostructures were synthesized by direct vapor phase (DVP) technique and consist of nanowires of dimension 30-65 nm in diameter and 5 microns in length. We characterized nanostructures using Photoluminescence (PL) and X-ray Photoelectron Spectroscopy (XPS) measurements. The current-voltage characteristics were carried with and without UV illumination under oxygen levels of 7.6 X 10E2 Torr and under vacuum. The photoresponse measurements indicated persistent conductivity trend for depleted oxygen conditions. The persistent conductivity is explained on the theoretical model that proposes the change of neutral anion vacancy to charged state.


Nanotech 2008 Conference Program Abstract