Fabrication and characterization of c-Si/porous-Si/CdS/ZnxCd1-xo heterojunctions for applications in nanostructured solar cells

Solar cells based on c-Si/porous-Si/CdS/ZnₓCd₁₋ₓO heterojunctions were synthesized by depositing CdS films on c-Si/porous-Si (PS) substrates by electrochemical deposition (ED). PS layers with systematically varied pore diameter (8÷45 nm) and were fabricated on p-type c-Si wafers using electrochemical etching. The window layers of ZnₓCd₁₋ₓO with several Zn concentrations(x=0.2; 0.4; 0.5 and 0.6) were also deposited on the CdS buffer layers by ED. The photoelectrical properties of heterojunctions were studied as functions of PS pore size and Zn content in ZnₓCd₁₋ₓO. The optimal pore size and Zn contents were found to be 10 nm and x=0.6, respectively. These yielded a solar cell sample exhibiting an efficiency of 9.9%, the maximum observed in this study.