Synthesis of a Cu₂ZnSnS₄ (CZTS) Absorber Layer and Metal Doped ZnS Buffer Layer for Heterojunction Solar Cell Applications

Abstract

A novel synthetic strategy was employed to fabricate a Cu2ZnSnS4 (CZTS) absorber layer using a quaternary compound target which has similar properties to that of copper indium gallium selenide (CIGS). A conventional R-F magnetron sputtering system was used to fabricate the CZTS absorber layers on glass substrates. The films were rapidly thermally annealed at 500 °C in a nitrogen atmosphere for 20 minutes to improve their crytallinity. The formation of a kesterite structure was confirmed using X-ray diffraction measurements. The improved crytallinity of the CZTS was observed with (112) oriented phase. The band gap of the as-deposited and annealed films was found to be 1.97 and 1.55 eV respectively. The films stoichiometry and morphology were observed using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) measurements. In addition; buffer layer of ZnS which was doped with metal elements; was fabricated by using a chemical bath deposition (CBD) technique.