Investigations on co-evaporated Cu2SnSe3 and Cu2SnSe3–ZnSe thin films

Cu2SnSe3 is an important precursor material for the growth of Cu2ZnSnSe4, an emerging solar cell absorber layer via solid state reaction of Cu2SnSe3 and ZnSe. In this study, we have grown Cu2SnSe3 (CTSe) and Cu2SnSe3–ZnSe (20%) films onto soda-lime glass substrates held at 573 K by co-evaporation technique. The effect of annealing of these films at 723 K for an hour in selenium atmosphere is also investigated. XRD studies of as-deposited Cu2SnSe3 and Cu2SnSe3–ZnSe films indicated SnSe as secondary phase which disappeared on annealing. The direct optical band gap of annealed Cu2SnSe3 and Cu2SnSe3–ZnSe films were found to be 0.90 eV and 0.94 eV respectively. Raman spectroscopy studies were used to understand the effect of ZnSe on the properties of Cu2SnSe3.