Multi-stage evaporation of Cu2ZnSnS4 thin films

Abstract Multi-stage evaporation is a well-established method for the controlled growth of chalcopyrite thin films. To apply this technique to the deposition of Cu 2 ZnSnS 4 thin films we investigated two different stage sequences: (A) using Cu 2 SnS 3 as precursor to react with Zn-S and (B) using ZnS as precursor to react with Cu-Sn-S. Both Cu 2 SnS 3 and ZnS are structurally related to Cu 2 ZnSnS 4 . In case (A) the formation of copper tin sulphide in the first stage was realized by depositing Mo/SnS x /CuS (1  x 2 SnS 3 can not be excluded. SEM micrographs reveal that films of sample type B are denser and have larger crystallites than for sample type A, where the porous morphology of the tin sulphide precursor is still observable. Solar cells of these absorbers reached conversion efficiencies of 1.1% and open circuit voltages of up to 500 mV.