Aqueous Synthesis of CuS Thin Film for Photodetector Application

Abstract

In this research work, the covellite copper sulfide (CuS) thin film has been deposited on the glass substrates by the cost-effective chemical bath deposition (CBD) method with a 1:4 molar ratio of copper and sulfur with a variation of annealing temperature. The structural, morphological, and electrical properties of the as-deposited CuS thin film and annealed at 100 °C, 200 °C have been investigated. The XRD, showing peaks at 29.2° and 47.9°, depicts the presence of the covellite phase of copper sulfide thin film (CuS). Raman spectroscopy reveals a strong prominent peak at 475 cm-1, corresponding to the vibration of the stretching mode of the S-S bond, which attributes the formation of the covellite phase of copper sulfide thin film. The crystallinity of CuS thin film is increased with an increase in the annealing temperature. The Hall effect measurement has revealed the p-type nature of CuS thin film. The mobility of CuS thin film is increased from 25.27 cm2/V.s to 35.45 cm2/V.s with annealing, while the resistivity is decreased. The current-voltage plot of CuS thin film shows the ohmic nature with Al metal. The CuS thin film, annealed at 200 °C, exhibits good response under illumination. The CuS thin film, annealed at 200 °C, possesses a carrier concentration of 4.28×1018 cm-3, and mobility of 35.45 cm2/V.s, which could be a suitable candidate for optoelectronic device applications.