Effect of Thickness on Structural, Optical and Electrical Properties of In2S3 Thin Films Grown by Thermal Evaporation for Solar Cell Buffer Layer Applications

A study on effect of thickness on the structural, optical and electrical properties of indium sulfide (In2S3) thin films is undertaken in this paper. The films of thickness 45 nm, 68 nm and 121 nm were deposited on glass and ITO coated glass substrates employing thermal evaporation method at room temperature. These films were subjected to X-ray diffractometer (XRD), UV-Vis spectrophotometer and source meter for structural, optical and electrical analysis respectively. The XRD results show that the In2S3 thin films are amorphous in nature. The optical band gap of films is varied in the range 2.06-2.57 eV and found to be decreased with thickness. The absorption and extinction coefficients are calculated and observed to be decreased with thickness while refractive index is increased. The optical analysis reveals that the films of 68 nm may be used in solar cell applications as buffer layer due to their optical energy band gap of 2.26 eV which coincides well with the ideal band gap of In2S3 thin films. The electrical analysis shows that the current-voltage characteristics are linear in nature. The resistivity is observed to be decreased with thickness while conductivity is increased. The results are in agreement with the available literature.