A high-speed photoconductive UV detector based on an Mg_0.4Zn_0.6O thin film

Abstract

A high quality MgxZn1−xO thin film with up to ∼40 at% Mg incorporation was grown on a quartz substrate by the rf magnetron sputtering technique. The photoconductive type of Mg0.4Zn0.6O metal–semiconductor–metal ultraviolet detector was prepared. The ratio of the ultraviolet to visible was more than four orders of magnitude; the 10%–90% rise and fall times were 16 ns and 250 ns, respectively. Furthermore, the dark current was below 40 nA under 3 V bias and the gain was observed which caused the high responsivity (∼1.3 A W−1) at 320 nm, and the corresponding detectivity D* was 1.37 × 1011 cm Hz1/2 W−1. A high-speed response was attributed to the high quality of the Mg0.4Zn0.6O thin film, which was found to dramatically enhance the UV detection properties of the device. The effect of the gain on the fall time and responsivity was analysed in the present work.