Impact of CdTe thin film thickness in ZnxCd1−xS/CdTe solar cell by RF sputtering

Abstract

This paper presents the impact of thickness of RF sputtered CdTe thin film as an absorber layer through structural and optical characterization in ZnxCd1−xS/CdTe solar cells at lower concentration of zinc (Zn). The crystallographic, morphological and optical properties of CdTe thin film fabricated on top of bare soda-lime glass were elucidated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and ultraviolet (UV) spectrophotometer. XRD spectra shows that crystallinity increases in thicker samples and the CdTe (1 1 1) diffraction peak intensity centered at 23.825° increases with the increase of film thickness confirming the zinc blend structure of CdTe thin film. The window layer ZnxCd1−xS was fabricated with optimum deposition conditions by co-sputtering of ZnS and CdS. The complete cell was fabricated by RF magnetron sputtering with the cell configuration of glass/FTO/ZnxCd1−xS/ZnTe/Ag. With the increasing thicknesses of CdTe the cell efficiency increases with the highest efficiency of 8.79% for 3.5 μm of CdTe. This paves the way of novel window of ZnCdTe for smoothening the junction mismatches in hetero-junction CdTe thin film solar cells.