PROPERTIES OF LOW-LEVEL Sn-DOPED In2S3 FILMS DEPOSITED BY SPRAY PYROLYSIS TECHNIQUE

Tin-doped indium sulfide films were grown on glass substrates by spray pyrolysis technique at low different Sn:In atomic ratio in the starting solution and optimum experiment conditions (T-s = 340 degrees C, S:In = 2). The tin to indium molar ratio Sn:In was varied from 0 to 4 x 10(-3) in the solution. The obtained films with 2 mu m of thickness, are perfectly adhered, homogenous and uniform on the substrates. X-ray diffraction study reveals that all the films are formed in beta phase grown preferentially along (400). These films lose the orientation with increasing tin doping level. The crystallite size of undoped film was 48.8 nm, which increases to 59.2 nm corresponding to the film grown with Sn:In = 4 x 10(-3). Raman analysis shows different peaks related to In2S3 phase. Optical analysis shows that these films are transparent in the visible and near IR with a transmittance higher than 85%. The optical gap energy is found to be direct and varies from 2.61 eV to 2.76 eV with the increase of Sn:In ratio from 0 to 4 x 10(-3). The films are n type and Sn doping improves considerably their conductivity. The photoluminescence behavior of In2S3:Sn films was also studied.