High-quality zinc oxide (ZnO) films were epitaxially grown on R-plane sapph
ire 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-semicon
ductor-metal ultraviolet sensitive photodetectors were fabricated on N-dope
d 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.