Faster photoresponse, enhanced photosensitivity and photoluminescence in nanocrystalline ZnO films suitably doped by Cd

Faster photoresponse, enhanced photosensitivity and photoluminescence are obtained in Cd doped nanocrystalline ZnO films obtained by sol-gel method. The rise and decay times decrease for 0.56 at% Cd doping and the photosensitivity increases by approximately 20% rendering the sample very useful for switching and UV detector applications. Comparatively larger surface to volume ratio occurs for this sample. Consistent switching behavior is obtained throughout. The films are optically transparent with crystallite size less than 22 nm. Optical band-gap is tuned between 3.22 and 3.15 eV by increasing the Cd doping slightly which compares favorably well with earlier reports. The NBE emission in the ultraviolet at 386 nm, from 0.51 at% Cd doped sample, is remarkably good with suppressed defect-emissions and six-fold higher intensity as compared to that from undoped sample. The surface roughness decreases with increase in dopant concentration.