Single step preparation of quaternary Cu2ZnSnSe4Cu2ZnSnSe4 thin films by RF magnetron sputtering from binary chalcogenide targets

Cu2ZnSnSe4Cu2ZnSnSe4 (CZTSe) thin films were grown in a single step procedure by RF magnetron sputtering from a compacted powder consisting of blended chalcogenides. Targets with various chalcogenide mole ratios were designed for the purpose of preparing stoichiometric as-grown films. The material concentrations of the films grown at room temperature were found to depend on the mole ratio of the chalcogenides in the targets. It was found that a significant deviation of material concentration of the films from ideal stoichiometry led to the formation of CuSe, ZnSe and SnSe secondary phases. CZTSe films with a stannite phase could be grown even at room temperature from the sputtering target containing Cu2SeCu2Se with corresponding growth orientations of (101), (112), (220/204), (312/116) and (332/316). The p  -type CZTSe film grown at a substrate temperature of 150∘C showed a high absorption coefficient of 104cm-1 with an optical band gap of 1.56 eV, resistivity as low as 1.482Ωcm and carrier concentration of 1×1019cm-3. These results suggested that the control of the target compositions was crucial to grow single phase and stoichiometric quaternary CZTSe films.