Property characterizations of Cu2ZnSnSe4 and Cu2ZnSn(S,Se)4 films prepared by sputtering with single Cu–Zn–Sn target and a subsequent selenization or sulfo-selenization procedure

Abstract

Cu2ZnSnSe4 (CZTSe) and Cu2ZnSn(S,Se)4 (CZTSSe) films were prepared by sputtering of single metallic Cu–Zn–Sn target and subsequent selenization or sulfo-selenization at 550−650°C. Selenization aided by SnSe2 and CuSe2 obtained CZTSe with dense microstructure and large grain size of 8μm. Sulfo-selenization with SnSe2 and CuS pellets did not achieve large-grained CZTSSe. Substitution of Cu+ by Zn2+ to form ZnCu1+ donor and occupation of Cu+ at the B site of Cu2BIBII(S,Se)4 to form CuB2− acceptor are major defects that explain the relation between composition and electrical property, which are important material properties to evaluate CZTSe and CZTSSe films to be used as absorbers for solar cells.