Structural, Morphological and Optical Properties of Sol-Gel Derived ZnO Thin Film for UV Sensing Application

Abstract

In the current research we have studied the structural, morphological, optical and ultraviolet (UV) light sensing properties of ZnO thin film. The film was prepared by sol-gel technique and deposited on glass substrate by spin coating method. The structural analysis was performed by X-ray diffractometer (XRD) while the surface morphology and optical properties of the deposited thin film were monitored using field emission scanning electron microscope and UV-VIS spectrophotometer. The FESEM image displayed the homogenous coverage of ZnO nanoparticles over the surface of glass substrate. The deposited thin film shows an average transmittance value of more than 90%, in the visible light spectrum. The calculated value for optical band-gap was 3.26 eV. Refractive indices and dielectric constants were calculated by utilizing the bandgap value by considering different relations. Current to voltage characterization was conducted by using Kiethley sourcemeter connected with ultraviolet (UV) light illuminated LED’s. The excellent photo to dark current (Iph/Id) ratio (5.49) and rapid rise and decay time (15 s and 6 s) and the measured responsivity (1 A/W) suggest that the deposited ZnO thin film can be used for ultraviolet (UV) light sensing application.