Structure and optical properties of thin As2S3-In2S3 films

This paper deals with the optical properties of thin As2S3-In2S3 films. The thin layers were deposited by thermal co-evaporation of As2S3 and In2S3. The composition of the coatings was controlled by x-ray microanalysis; it was found to be close to the expected one. The refractive index n and optical band gap E-g(opt) were calculated from the transmittance and reflectance spectra. The results showed that the refractive index of thin As-S films is not affected by the addition of 1 at% indium and it increases from 2.46 to 2.58 for thin film with 13 at% In. A decrease in the changes in the refractive index, Delta n, after exposure to light or annealing with addition of indium in arsenic sulfide is observed. To explain the influence of the indium on the photoinduced changes in the optical properties of thin As-S-In films, the glass structure was investigated by infrared spectroscopy. The calculated values of the optical constants were compared with those obtained from ellipsometric measurements.