Optical and Electrical Properties of CuInS₂ Thin Films by Spray Pyrolysis

The optical, electrical and structural properties of CuInS 2 thin films prepared by spray pyrolysis have been studied. The polycrystalline films produced by spraying a solution of Cu (CH 3 COO) 2 H 2 O, InCl 3 and (NH 2 ) 2 CS with the atomic ratio Cu:In:S=1:1:2.8∼1:1:3.2 and annealing at 500°C for 2 hours were nearly stoichiometric, and the depth profiles of the atomic composition were flat except near the surface. The optical band gap at room temperature was 1.43 eV, and the polarity of the thermoelectromotive force showed p-type conduction at a sulfur concentration ratio to Cu[S]≥2.8. The activation energy of conductivity was 0.3 eV.