CdCl2 treatment concentration evolution of physical properties correlation with surface morphology of CdTe thin films for solar cells

摘要

The microstructural, optical and electrical properties of a thin film could be tuned by the post-treatments such as high-temperature processing and CdCl2 treatments. The microstructural and optoelectronic properties of e-beam evaporated CdTe thin films were investigated and optimized with the application of CdCl2 treatments and correlated with the surface morphology. The films of thickness 1.05 mu m were grown on glass and ITO substrates followed by wet CdCl2 treatment and then heat treatment at 450 degrees C. The direct band gap is found to decrease from 1.75 eV to 1.48 eV with the treatment. The dielectric theory, Herve-Vandamme, Swanepoel and DiDomenico models were employed to analyze some optical and dielectric constants. The zinc blende cubic structure is found and crystallographic parameters are also briefly discussed. The electrical conductivity and IR transmittance were found to be increased with increasing concentration of CdCl2. The results revealed that CdCl2 treatment has significant effect on these properties.