A MICROSTRUCTURAL STUDY ON THE SURFACE AND INTERFACE OF CDTE CDS SOLAR-CELLS/

The surface and interface properties of CdTe/CdS solar cells, includin g interfacial mixing, surface and interface geometrical morphology, Cd Te grain size and preferential crystal orientation of CdTe layers were studied using Auger electron spectroscopy (AES) depth profiling, atom ic force microscopy (AFM), Fourier transform infrared (FTIR) spectrosc opy, optical reflectance (OR) and X-ray diffraction (XRD) techniques. The correlation between the surface and interface properties and CdTe/ CdS solar cell performance was also investigated. AES depth profiling was used to analyse the interdiffusion between the CdTe and CdS layers . Atomic force microscopy (AFM) suggests that the interfacial geometri cal morphology has a significant influence on the photovoltaic propert y of CdTe/CdS solar cells. Rough interfaces tend to increase the photo voltaic conversion efficiency of solar cells because of multiple refle ctions. X-ray diffraction shows that polycrystalline CdTe/CdS solar ce lls with higher efficiencies appear to be orientated with more (111) p lanes of CdTe parallel to the macrosurface, but CdTe single crystals w ith differently indexed surface planes show almost the same reflection behaviour. Further theoretical and experimental analyses are therefor e needed to clarify this observation.