Ultraviolet detectors based on epitaxial ZnO films grown by MOCVD

High-quality zinc oxide (ZnO) films were epitaxially grown on R-plane sapphire substrates by metalorganic chemical vapor deposition at temperatures in the range of 350 degrees C to 600 degrees C. In-situ nitrogen compensation doping was performed using NH3. Microstructural and optical properties of the films, as well as the N-doping effects, were studied. The metal-semiconductor-metal ultraviolet sensitive photodetectors were fabricated on N-doped epitaxial ZnO films. The detector showed fast photoresponse, with a rise time of 1 mu s and a fall time of 1.5 mu s. Low-frequency photoresponsivity, on the order of 400 A/W at 5 V bias, was obtained.