Effect of Ar-plasma treatment and annealing on thermally evaporated β-In2S3 thin films

In the present study, the effect of annealing and Ar-plasma treatment on structural, morphological and optical properties of thermally evaporated β-In2S3 thin films has been investigated. During Ar-plasma treatment, some interesting results were observed that an array of metallic indium nanostructures was formed over In2S3 film surface with quasi-spherical or spread droplet shapes of an average size of 20–100 nm in the lateral direction and a height of less than 70 nm. Here, the Ar-plasma treatment serves as a new strategy for the self-formation of metallic indium nanostructures over the film surface. Further, the optical absorption of In2S3 films has been enhanced from 104 to 107 cm−1 while the optical band gap energy decreased from 2.71 eV to 2.50 eV after Ar-plasma treatment. The metallic nanostructures loaded on semiconductor surface can act as an electron trap that can effectively prevent the recombination of photo-generated electron-hole pairs.