Effect of Substrate temperature on Structural and Optical properties of In2S3 thin films grown by Thermal evaporation

Abstract

Indium sulfide (In2S3) is widely used as a buffer layer alternative to CdS for thin film solar cell applications. In2S3 thin films were deposited on glass substrates by using thermal evaporation technique at different temperature that vary in the range, 200-350°C. The effect of substrate temperature (Ts) on structural and optical properties of In2S3 films was investigated by using Grazing incidence X-ray diffraction (GIXD), Raman Spectroscopy and Photon RT Spectrophotometer. The GIXD patterns showed that the films grown at 200°C and 250°C were amorphous in nature. For further increase of temperature Ts=300°C and 350°C, the films showed polycrystalline nature with mixed phases of tetragonal and cubic structure of β-In2S3 with (300) plane as preferred orientation. Also, it was observed that the crystallinity of the films increased with substrate temperature. Raman Spectroscopy analysis confirmed that the active modes present belong to the β-In2S3 phase. From the optical transmittance spectra, the band gap of the as-grown In2S3 films was evaluated that varied in the range, 1.72-2.64 eV. Further, the optical constants such as refractive index (n) and extinction coefficient (k) were also calculated for as-deposited In2S3 thin films, and the results were reported.