Highly Selective Behavior of Thin Film ZnO Based Homojunction Photodetector for UV Sensing

ZnO is considered as a prominent semiconductor material in the II-VI metal-oxide group due to its exceptional optical properties that persuade many researchers to use it in the fabrication of photodetectors for ultraviolet (UV) sensing applications.The sensitivity of a photodetector is measured in terms of its responsivity.In this article, the authors have reported a p-n homojunction based on nanostructured ZnO thin film for application as a photodetector in the UV region.The p-type nature of ZnO was obtained by selective doping of ZnO with copper.Hall and hot point probe measurements confirmed that the deposited Cu doped ZnO (CZO) thin film poses p-type conductivity with a resistivity of 0.9 Ωcm, carrier concentration of 1.0287  10 18 cm -3 and mobility of 6.5 cm 2 /Vs at room temperature.The crystalline, morphological studies of ZnO films have been performed by X-ray diffractometer (XRD), atomic force microscopy (AFM), energy dispersive spectrum (EDAX).The current-voltage (I-V) measurements under dark and illuminated conditions have been carried out using Semiconductor Device Analyzer (SDA).The fabricated device shows good rectification property with low reverse leakage current and high rectification ratio.The device has been found to be stable and exhibiting a high value of responsivity (3.2 A/W) at 376 nm for a reverse bias voltage of 3 V.The performance of the new p-n junction ZnO based UV detector is found to outstrip the existing ZnO based Schottky diode photodetectors.