Fabrication and Performance of UV Photodetector Based on Nanostructure ZnO Thin-Film Deposited by Vacuum Coating Technique

Abstract

The paper reports fabrication, characterization and testing of the thermal stability of Pd/nanostructured ZnO thin-film Schottky diode. The effect of optical power and bias on the performance of fabricated diodes based UV photodetectors has been investigated. ZnO was grown on p-type Si 100 substrate by vacuum thermal evaporation technique. The surface morphological and the structural properties of the thin-film were studied by scanning electron microscopy and X-ray photoelectron spectroscopy measurements. I-V characteristics of the Schottky barrier UV photodetector were studied and the parameters such as ideality-factor, leakage-current, rectification ratio and barrier-height were extracted from the measured data at room temperature (300K). The study revealed that the performance of the devices has a thermal stability with increasing post metal deposition annealing temperature up to 500?C. For annealing temperatures beyond this temperature the rectification quality of the device degrades drastically. The device exhibited high efficiency and high sensitivity under the reverse bias condition. For forward bias, the UV detection sensitivity decreased proportionally to the bias voltage. At lower level of UV optical power (0.05 to 0.5 mW) the Schottky barrier height and rectification ratio decreased rapidly while at higher level of optical power (5 to 10 mW) these parameters decreased gradually. © 2015 IEEE.