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Proceedings Paper

Optical properties of metal-semiconductor-metal ZnO UV photodetectors
Author(s): Linghui Li; Yungryel Ryu; Henry W. White; Ping Yu
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Paper Abstract

Among wide bandgap materials that are sensitive to photons in the ultraviolet (UV) region, ZnO is a promising photonic material because of its unique optoelectronic properties. Based on the lateral interdigitated back-to-back Schottky contact structure on ZnO film, metal-semiconductor-metal (MSM) photodetectors have substantially lower parasitic capacitance compared with vertical p-i-n photodetectors, which leads to a very high speed photodetection. In this paper, we report optical characteristics of MSM ZnO UV photodetectors for which ZnO films were fabricated by hybrid beam deposition. An annealing process was used in oxygen ambient. The MSM ZnO photodetector consists of two interdigitated electrodes both with Ti/Au metals on an n-type ZnO thin film. The electrodes on the photodetector are finger-shaped. We found that the annealing process decreases contact resistance and photoresponse time. The possible mechanism of annealing process is the removal of surface defects created in the fabrication process. A sublinear power dependence of photocurrent reveals the existence of a light induced space charge region inside the ZnO film. The device displays fast pulse response with a very short rise time and a relatively long relaxation time with applied bias. The exponential decay tail indicates an RC type time response.

Paper Details

Date Published: 16 February 2010
PDF: 9 pages
Proc. SPIE 7603, Oxide-based Materials and Devices, 76031A (16 February 2010);
Show Author Affiliations
Linghui Li, Univ. of Missouri, Columbia (United States)
Yungryel Ryu, MOXtronics, Inc. (United States)
Henry W. White, Univ. of Missouri, Columbia (United States)
MOXtronics, Inc. (United States)
Ping Yu, Univ. of Missouri, Columbia (United States)

Published in SPIE Proceedings Vol. 7603:
Oxide-based Materials and Devices
Ferechteh Hosseini Teherani; David C. Look; Cole W. Litton; David J. Rogers, Editor(s)

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