Growth optimization of Zn_xCd_1-xS films on ITO and FTO coated glass for alternative buffer application in CdTe thin film solar cells

In this study, Zn_xCd_1-xS/CdTe solar cells were fabricated on commercially available indium tin oxide (In₂O₃: Sn or ITO) and fluorine doped tin oxide (SnO₂: F or FTO) soda-lime glass (SLG) substrates by RF magnetron sputtering. Thin Zn_xCd_1-xS window layers with lower zinc (Zn) content in comparison to cadmium (Cd) were deposited by co-sputtering of ZnS and CdS targets concurrently by changing the radio frequency (RF) power of both during sputtering. CdTe thin films for the complete cells were also grown by sputtering with different thickness. Prior to fabricating the complete device, characterization for growth optimization of Zn_xCd_1-xS window layer and CdTe absorber layer was performed by utilizing Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Ultraviolet–visible spectroscopy (UV–Vis), Field Emission Scanning Electron Microscopy (FESEM) and Hall effect measurement system. Complete Zn_xCd_1-xS/CdTe solar cells were fabricated with the optimized growth conditions of window and absorber layers. The best cell fabricated on ITO coated SLG substrates showed an efficiency of 8.08% with significant open circuit voltage (V_oc) of 882 mV.