On the conversion of amorphous In2S3 thin films to polycrystalline In2S3 and to In2O3 through thermal oxidation process

Abstract

Indium sulfide (In2S3) and Indium oxide (In2O3) are promising n-type semiconductors that have been used in optoelectronic applications owing to their unique optical and electrical properties. In this work, amorphous In2S3 thin films were grown by co-evaporation technique. The as-deposited films are subjected to air annealing process in the temperature range of 300–550 °C. In2O3 thin films were obtained through the oxidation process of the as-prepared In2S3 thin films. X-ray diffraction patterns reveal that as-deposited films are amorphous in nature and are systematically converted into polycrystalline In2S3 and then to In2O3. The energy dispersive X-ray spectroscopy results also confirm the transformation of In2S3 films into In2O3. The obtained direct energy band gap of In2S3 films is in the range of 2.47–2.85 eV and the direct energy band gap of In2O3 film found to be 3.48 eV. The resistivity of as-deposited film is 2.04 × 102 Ωcm and it decreases to 8.17 × 10-2 Ωcm for the films annealed at 550 °C. The obtained results show that the In2S3 and In2O3 thin films could be a right choice for buffer layer and transparent conducting oxide layer respectively for thin film solar cell applications.