Cu2ZnSnS4 thin films grown by flash evaporation and subsequent annealing in Ar atmosphere

A study of Cu2ZnSnS4 thin films grown by flash evaporation and subsequently annealed in Ar atmosphere has been carried out. Prior to thin film deposition, Cu2ZnSnS4 bulk compounds with stoichiometric and Zn-rich compositions were synthesized as evaporation sources. The characteristics of the bulk compounds and thin films were investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and elastic back scattering. Cu2ZnSnS4 deposited films contain lower concentrations of Zn than the bulk compounds used as evaporation sources, which is related to a preferential Zn re-evaporation during the deposition process. The desired kesterite composition for solar cell applications was achieved by using a Zn-rich compound as the evaporation source plus a thermal treatment at 620 °C in Ar atmosphere.

► Cu2ZnSnS4 (CZTS) thin films by flash evaporation + annealing in Ar atmosphere
► Difficulty of growing a single phase kesterite material
► X-ray diffraction and Raman spectroscopy to identify the different phases
► Importance of the starting film composition to get the desired CZTS material
► Annealing treatment to obtain the optimum material to be used for CZTS solar cells.