Effect of temperature on optical properties of CuInS2 thin films

Polycrystalline CuInS2 thin films were grown by Spray pyrolysis method. This films have been deposited onto the glass substrate by varying substrate temperature from 275 0 C, at the interval of 25 to 350 0 C by using aqueous solution of Cupric chloride, Indium tri-chloride and thiourea of 0.02 M and Seems to be more important parameters affecting physical properties of the semiconductor. On account for the temperature dependent optical properties of polycrystalline CuInS2 thin films, grain boundary states were operative in nature. The values of absorption coefficient, extinction coefficient, refractive index, and dielectric constant have been calculated from the optical measurements. The prepared films at different substrate temperatures were found to have high transmittance (76 %) with the lowest thickness approximately t = 0.126 μm and at low transmittance (50 %) of the films with highest thickness nearly equal to t = 0.2163 μm. Due to temperature variation, the atoms are arrange regular in manner compound of CuInS2 films are investigates. As the films are not doped intentionally, defect observed in intrinsic nature by Sulphur interstitials. The most significant results in present study, the temperature varied with thickness of the film can be used to modify the optical band gap, extinction coefficient, refractive index and real-imaginary part of dielectric constants of CuInS2 thin films. KeywordsSpray pyrolysis, CuInS2 Ternary Semiconductor, Optical Constants