ZnO Schottky ultraviolet photodetectors

We present the results of Schottky UV photodetectors fabricated on n-tyPe ZnO epitaxial films. The ZnO films were grown on R-plane sapphire substrates by metalorganic chemical vapor deposition. The metal-semiconductor-metal (MSM) photodetectors were fabricated by using Ag os Schottky contact metal. For comparison, ZnO photoconductive detectors were also fabricated by using Al as ohmic contact metal. 1 V characteristics of these devices were analyzed. At a reverse bias of 1V, the circular Schottky photodiode exhibits a leakage current approximately 5 orders of magnitude smaller than that of its photoconductive counterpart. The photoresponsivity of the ZnO Schottky type MSM UV detector is 1.5 A/W and the leakage current is about 1 nA at 5 V bias. The detector shows a fast photoresponse component with a rise time of 12 ns and a hill time of 50 ns. (C) 2001 Elsevier Science B.V. All rights reserved.