Electrical and UV detection properties of ZnO thin film based schottky contacts deposited by RF magnetron sputtering

Abstract

This paper reports structural, electrical, and ultraviolet (UV) light detection properties of Au and Pd/n-ZnO thin film Schottky diodes. ZnO thin films were deposited over glass and p-Si substrates using RF magnetron sputter deposition. The crystalline structure, surface morphology and optical properties of the grown ZnO thin films were investigated by X-ray diffractometer (XRD), Atomic force microscope (AFM), photoluminescence spectroscope (PL) and UV-vis spectrophotometer. The grown ZnO thin films were polycrystalline in nature with a homogenous surface morphology, as evident from the XRD, SEM and AFM analyses. The optical study confirms that the ZnO thin film has a good absorbance in UV region and it is ‘visible blind’. The ZnO thin film was then used to fabricate the Pd/n-ZnO and Au/n-ZnOSchottky contacts/photodiodes for UV detection at 365 nm. The electrical properties of fabricated Schottky contacts/photodiodes have been investigated using current-voltage (I-V) measurement. The fabricated Pd/n-ZnO and Au/n-ZnOSchottky contacts/photodiodes exhibited good rectifying characteristics with a rectification (IF/IR) ratio of 2392 and 2700, respectively. Upon illumination of these contacts/photodiodes with UV light, we observed the photo responsivity to be 0.134 and 0.182A/W respectively. The fabricated device has a potential to be used as a sensitive UV detector.