Tin doped β-In2S3 thin films prepared by spray pyrolysis: Correlation between structural, electrical, optical, thermoelectric and photoconductive properties

In this research, Sn-doped In2S3 thin films were prepared on glass substrates by spray pyrolysis technique. The effect of tin impurity on the structural, morphological, electrical, thermo-electrical, optical and photoconductive properties of films has been investigated. The tin to indium atomic ratios (x = [Sn]/[In]) were varied from 0 to 0.15 in the spray solution. X-ray diffraction analysis showed the formation of cubic beta-In2S3 phase in all deposited films. Scanning electron microscopy images indicated that nanostructure of the condensed films has a particle-cluster to rock-plate growth type. The Hall effect measurements have shown n-type conductivity in all deposited films. The lowest resistance of 1.3 M Omega/square and the highest the carrier concentration of 3.93 x 10(18) cm(-3) were obtained for the film deposited with x = 0.08. The maximum of the Seebeck coefficient equal to 132 mu VK-1 was obtained at 400 K for the film deposited with x = 0.15. The average transmittance of films varied over the range of 40-60%. The band gap values of samples were obtained in the range of 2.89-3.75 eV for direct and 2.61-3.37 eV for indirect allowed transitions. From the photoconductivity studies, the sample prepared with x = 0.05 exhibited the highest photoconductivity among the In2S3:Sn films. (C) 2013 Elsevier B.V. All rights reserved.