Spray coated nano-crystalline lead sulfide thin film for photo-detector application

Abstract

In this paper, we report a photo-detection property of a nano-crystalline lead sulfide (PbS) thin film under infra red light illumination. Nano-crystalline PbS films are fabricated by a spray pyrolysis method on glass substrate, from a aqueous precursor solution at 250 °C. Photo-detector devices are prepared by drawing finger contacts using silver paste on the film. Structural and morphological analysis of the film confirmed the deposition of nano-crystalline PbS film with∼50 nm crystallites and uniform coating of PbS thin film on glass substrate with a surface roughness of∼7.7 nm. The linear I-V measurement performed in dark and under light illumination shows low resistive contact between silver electrode and PbS film. The photo-sensitivity, the response time and the decay time were measured under illumination of PbS film by 100 Watt tungsten lamp. Photo-sensitivity measurements of PbS based photo-detector reveal the excellent sensitivity of∼50 at 10 V. For this photo-detector the best response and decay time is observed to be 36 and 16 ms, respectively. This simple and low cost fabrication method results in a photo-detectors device, which have fast response and decay time.