Effect of substrate temperature on nebulized spray pyrolysised In₂S₃ thin films

Nebulized spray pyrolysis is a simple and cost effective technique for the preparation of In₂S₃ thin films. In₂S₃ compound thin films were deposited on glass substrates at substrate temperatures from 200 to 350 °C in steps of 50 °C by nebulized spray pyrolysis technique. These films were shiny, thin and uniform, which were evidenced by specular reflections of white light due to multiple internal reflections of coherent rays. They were characterized by X-ray diffraction (XRD), optical transmittance, scanning electron microscope imaging (SEM), energy dispersive analysis by X-rays and electrical conductivity. Cubic structure with preferential orientation along (111) plane was observed from XRD analysis. SEM analysis revealed that all the films have no voids and cracks. Direct band gap values were found to decrease up to 2.69 eV with increase in substrate temperature from 200 to 300 °C, but increased further, whereas the indirect band gap values were found to increase up to 2.14 eV with increase in substrate temperature from 200 to 300 °C, and decreased further. All the films were found as n-type semiconductors. The resistivity of all the samples decreased with increase in substrate temperature. A maximum carrier concentration value of 7.36 × 10¹⁸ cm⁻³ was obtained for the film grown at substrate temperature of 300 °C. The carrier mobility was increased up to 86.2 cm²/Vs by increasing the substrate temperature from 200 to 300 °C and then it decreased to 17.6 cm²/Vs at a substrate temperature of 350 °C.