Effect of composition on the structural, optical and electrical properties of sprayed Sb2S3 thin films prepared from non-aqueous medium Original Research Article

Sb2S3, in the thin film form, is important in view of its photosensitive and thermoelectric properties. Sb2S3 thin films have been spray deposited onto amorphous glass substrates using acetic acid (glacial) as a non-aqueous solvent. The films have been prepared by spraying, a mixture of equimolar SbCl3 and CS(NH2)2 dissolved in acetic acid, onto the glass substrates maintained at optimised conditions of substrate temperature (250°C) and solution concentration (0.1 M). The spray rate, during deposition of the films, was maintained to be 12 cm3 min−1. The films have been deposited with varying Sb:S volume ratio in the solution: 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2 and 9:1. The films have been characterised for their structural, optical and electrical properties. The X-ray diffraction studies reveal that the deposited material is polycrystalline Sb2S3. It has been found that as the composition of Sb increases from 1 to 4, crystallinity of the material increases continuously. It is relatively higher for 4:6 composition and continuously goes on decreasing for further subsequent compositions. The calculated lattice constants for orthorhombic crystal structure of Sb2S3 for the film deposited with composition 4:6 are a=11.18, b=11.33 and respectively. The grain size has been found to vary from 265 to 350 Å with composition. The room temperature electrical resistivity is of the order of 107–108 Ω cm. The calculated activation energy is found to be 0.86 eV for the film with composition 4:6. Optical absorption studies reveal that the material formed has a direct energy gap of 1.88 eV.