Electrical Properties of CSS Deposited CdTe Thin Films for Solar Cell Applications

Abstract

CdTe is a very potential absorber material for thin film solar cell application. In this work CdTe thin films (TF) were deposited on CdS thin films by close-spaced sublimation (CSS) technique at different source and substrate temperature in inert gas condition. To bring out the optimum temperature set for CSS deposited CdTe films, several experiments were done. The process pressure of the chamber during deposition was maintained at 1.5 Torr in a dynamic condition. The effects of deposition temperature on the electrical properties of the as-deposited CdTe films were investigated by Hall Effect measurement. The films were deposited at 610 °C, 630 °C, 650 °C and 670 °C source temperatures. The first three films showed p-type conductivity while n-type conductivity appeared in the film deposited at 670 °C. The hole concentration of the as-grown p-type CdTe films followed an upward trend with the increase of source temperature and it reached a peak value at 650 °C. The highest hole mobility was observed for the lowest source temperature. However, the resistivity of the CdTe films was found increasing with the increase of source temperature. Thus, the CdTe thin film deposited at 650 °C showed better electrical properties for solar cell applications.