Sol-Gel-Based Highly Sensitive Pd/n-ZnO Thin Film/n-Si Schottky Ultraviolet Photodiodes

High-performance ultraviolet (UV) Schottky photodiodes obtained by growing Pd Schottky contacts on the sol-gel-derived n-ZnO thin films deposited on n-Si substrates have been reported in this paper. The current-voltage (I-V) measurements of the as-fabricated Schottky photodiodes show an excellent room temperature contrast ratio (i.e., the ratio of the current under UV illumination to the dark current) of similar to 5.332 x 10(3) and responsivity (i.e., the parameter characterizing the sensitivity of the device to the UV light) of similar to 8.39 A/W at -5 V reverse bias voltage, respectively; when the device is illuminated by an UV source of similar to 650 mu W output power at similar to 365 nm. The measured room temperature contrast ratio and responsivity are believed to be the highest among the reported values in the literature for ZnO thin film-based Schottky photodiodes using sol-gel method.