Ultraviolet photoconductive detectors based on Ga-doped ZnO films grown by molecular-beam epitaxy

A high-quality Ga-doped ZnO film was epitaxially grown on a R-plane sapphire substrate by plasma-assisted molecular-beam epitaxy. Photoconductor devices with Al/Ti Ohmic contacts were fabricated. Photoluminescence and photocurrent measurements were carried out to study the emission and absorption properties of the Ga-doped ZnO film. Both spectra are consistent with each other showing good response in the ultraviolet region and weak response in the green-yellow band. Peak responsivity of 1.68 A/W at 20 V bias for 374 nm light was obtained in the ultraviolet region. Transient response of the device is slow due to the presence of the deep levels. (c) 2007 Elsevier Ltd. All rights reserved.