Optical characterization of In2S3-SiO2 nanocomposite thin films synthesized by sol-gel technique

In2S3-SiO2 nanocomposite films (with molar ratios of In2S3:SiO2 = 15:85, 10:90 and 5:95) were prepared on quartz substrates by sol-gel method. Highly confined nanoparticles of In2S3 (radius ~1.8-7 nm) were obtained in SiO2 matrix, indicating SiO2 to be a good capping agent for the nanoparticles. The films were annealed in air at different temperatures (473-623 K) and characterized by optical, microstructural and photoluminescence measurements. XRD studies showed that annealing in air upto 623 K leads to the formation of oxide free In2S3 nanoparticles. The broad Photoluminescence peak observed at ~353 nm showed a marked blue shift associated with a decrease in intensity with increasing concentration of In2S3 in the matrix.