Study of the band--gap shift in CdS films: Influence of thermal annealing in different atmospheres

Abstract

We study by photoacoustic spectroscopy the band--gap shift effect of CdS films. The CdS films were grown by chemical bath deposition and exposed to different annealing atmospheres over a range of temperature in which the sample structure is observed to change. We show the band--gap evolution as a function of temperature of thermal annealing and determine the process which produces the best combination of high band--gap energy and low resistivity. It allows us to know a possible procedure to obtain low--resistivity CdS/CdTe solar cells with high--quantum efficiency.