Impact of thin layer of copper on cadmium telluride and cadmium sulfide thin films

The present paper focuses on the study of influence of copper incorporation in the cadmium telluride (CdTe) films. CdTe absorber layers have been grown by thermal evaporation technique and cadmium sulfide (CdS) buffer layers have been deposited by Chemical bath deposition method. Copper incorporated CdTe films have been characterized by X-ray diffraction (XRD), Atomic force microscopy (AFM), scanning electron microscopy (SEM), UV–Vis spectroscopy, Raman spectroscopy and Hall Effect measurements. XRD analysis illustrated that all the CdTe thin films were of polycrystalline nature possessing cubic structure showing sharp peak at (111) orientation, while the intensities of peaks varied from sample to sample with respect to copper incorporation in the CdTe films. SEM analysis demonstrated that maximum grain size and morphology were dependent on the incorporation of copper on buffer layer. From the AFM results, it was observed that the surface roughness of CdTe thin films varied with respect to different copper incorporation in the thin films. From the Raman spectra analysis, it was observed that the intensities of A1, E1 modes of Te and TO modes of CdTe thin films varied with copper incorporated sample displaying maximum intensities of the shoulder peaks followed by other samples. From the optical properties of CdTe thin films it was demonstrated that bandgap of samples slightly decreased with higher copper amount. From the electrical properties of CdTe thin films it was observed that higher mobility and reduced resistivity were observed for copper incorporated samples. Thus, all these characterization results suggest that with controlled amount of copper incorporation these CdTe thin films possess the potential to be used as absorber layer for solar cells.