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.