We have investigated the photoconductivity and photocatalytic properties of polycrystalline zinc oxide (ZnO) films grown on c-plane sapphire substrates. Zinc-metal films where grown on sapphire substrates via dc-sputter deposition at room temperature with subsequent thermal annealing in air at 300°C, 600°C, 900°C, and 1200°C. Photoluminescence spectra indicate four emission bands: excitonic ultraviolet, blue, and deep-level green and yellow emission. The ratio of deep-level green emission to UV excitonic emission was observed to decrease with decreasing annealing temperature from 1200°C to 300°C. Metal-semiconductor-metal (MSM) Al:ZnO:Al planar UV photodetectors where fabricated via sputter deposition of aluminum ohmic contacts on the resulting ZnO films. Decreasing photocurrent is seen for increasing annealing temperature, which is consistent with PL studies. A responsivity of ~0.1 A/W was observed. Photocatalytic activity follows half-order reaction kinetics as determined by photodegradation of Rhodamine B.

Date Published: 29 February 2012
PDF: 8 pages
Proc. SPIE 8263, Oxide-based Materials and Devices III, 82631M (29 February 2012); doi: 10.1117/12.906227

Published in SPIE Proceedings Vol. 8263:
Oxide-based Materials and Devices III
Ferechteh H. Teherani; David C. Look; David J. Rogers, Editor(s)