Structure and photoresponse characteristics of ZnO thin films grown at high oxygen partial pressure

ZnO thin films were deposited by pulsed laser deposition on SiO2/Si substrates at high oxygen partial pressures of 2, 20 and 200 Pa, respectively. The structure, surface morphology and photoluminescence of the ZnO thin films were investigated. Metal–semiconductor–metal structure prototype detectors were fabricated with ZnO thin films, and their spectral response properties were characterized and discussed. ZnO films deposited at higher oxygen pressure exhibit lower out-of-plane residual compressive stress, larger crystallite size and lower concentration of deep-level defects. Detectors based on ZnO thin films grown at 20 and 200 Pa show no response in visible region. The UV response property of ZnO film grown at 20 Pa oxygen pressure is better than that at 2 and 200 Pa, which may be related to its good crystallinity, smooth surface and less deep-level defects.