Anomalous behavior of silver doped indium sulfide thin films.

The effect of doping spray pyrolyzed thin films of In₂S₃ with silver is discussed. It was observed that silver diffused into In₂S₃ films in as deposited condition itself. Depth profile using x-ray photoelectron spectroscopy clearly showed diffusion of silver into In₂S₃ layer without any annealing. X-ray analysis revealed significant enhancement in crystallinity and grain size up to an optimum percentage of doping concentration. This optimum value showed dependence on thickness and atomic ratio of indium and sulfur in the film. Band gap decreased up to the optimum value of doping and thereafter it increased. Electrical studies showed a drastic decrease in resistivity from 1.2×10³ to 0.06 Ω cm due to doping. A sample having optimum doping was found to be more photosensitive and low resistive when compared with a pristine sample. Improvement in crystallinity, conductivity, and photosensitivity due to doping of spray pyrolyzed In₂S₃ films with Ag helped to attain efficiency of 9.5% for Ag/In₂S₃/CuInS₂/ITO (indium tin oxide) solar cell. [ABSTRACT FROM AUTHOR]