Nano-crystalline CdS thick films: a highly sensitive photo-detector

Abstract

This work reports a simple method for fabrication of highly sensitive photo-detector based on uniform nano-crystalline CdS thick films deposited on glass substrate by spray pyrolysis technique. The presented photo-detector platform contains CdS thick films (3, 6, 9, 12 and 15 μm) and Ag electrode structure. In order to detect incident light signals, changes in electrical signals were measured (conductance and current). For photo-detection, the current response between the 'ON' and 'OFF ' states of incident light was measured when exposed to different wavelengths ranging from 450 to 700 nm. The fabricated device showed significant detection of low-power (∼5 mW cm−2) light for optimized film thickness of 12 μm. Time response measurements at different wavelength show fast response and decay time (25 ms) and high photo sensitivity (1123) at low bias voltage, indicating good quality of the deposited 12 μm thick CdS film.