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.