ZnO Thin Films Prepared Using the Ultrasonic Spray Pyrolysis Method for High Performance Metal Oxides-Based Photoconductors

Abstract

Zinc oxide (ZnO) has attracted considerable attention because of its potential applications in optoelectronic devices. Many scientists have reported on the preparation of ZnO based photodetectors in metal-semiconductor-metal (MSM) structures where expensive noble metals are used as electrodes. Here, we propose the preparation of full metal-oxide photoconductors by using indium tin oxide (ITO) as the electrodes and ZnO thin films as sensing materials. ZnO thin films were prepared by employing a simple ultrasonic spray pyrolysis (USP) technique with a commercial ultrasonic nebulizer (1.7 MHz). In this work, we developed a high performance ZnO based photodetector on interdigitated ITO with a simple and low-cost USP method. The I-V characteristic shows that ZnO thin film works in a photoconductive mode and has better performance as a UV (325 nm) detector than other wavelengths (505, 625 and 810 nm). As a UV detector, the devices exhibit high sensitivity (1255.51%), high responsivity (22.6 x 103 A/W), high detectivity (1.49 x 1014 Jones), good stability, a fast response time of 0.87 s and a relatively slow recovery time of 34.8 s. This high performance may be related to the large crystallite size that facilitates higher electron mobility.