Microstructural, optical, and electrical characteristics of Cu-doped CdTe nanocrystalline films for designing absorber layer in solar cell applications

This paper reports the microstructure, optical, and electrical characteristics of undoped and Cu-doped CdTe nanostructured thin films prepared on glass substrates by electron beam evaporation technique. The crystallographic study of X-ray diffraction shows that CdTe and Cu-doped CdTe films crystallize in the form of a cubic zinc blende structure. Microstructure analysis reveals that as the Cu-doping level increases, the average crystallite size increases, while the microstrian decreases due to the improvement of the crystallinity, thereby reducing defects. XRD and AFM investigations confirmed the nanostructure characteristic of undoped and Cu-doped films. It was found that the optical band gap energy increases from 1.485 to 1.683 eV as the Cu concentration increases from 0 to 10 wt%, which may be related to the Burstein–Moss effect. The refractive index is calculated from the Swanepoel envelope method and …