Utilization of spray coated nano-crystalline cadmium sulfide thin film for photo-detector application

Abstract

In this work, we report fabrication of high quality visible light photo-detector based on nano-crystalline cadmium sulfide (CdS) thin film deposited on glass substrate using spray pyrolysis technique. Structural, morphological and chemical analysis of the film confirms uniform coating of sulfur deficient nano-crystalline CdS thin film with ~ 30 nm crystallites. Finger electrodes were made on the film using Ag paste. Photo-detection property of nano-crystalline CdS thin films was tested under visible light illumination and the response of incident light in terms of photo-current was monitored when exposed at various light intensities ranging from 5 to 320 mW/cm2. The fabricated device showed highly sensitive and repeatable photo-detection at 10 V for low power 5 mW/cm2 light. Time response measurements at different wavelength show ultra-fast response (0.67 ms) and decay (0.86 ms) time and high photo sensitivity at low bias voltage.