Single step preparation of quaternary Cu2ZnSnSe4 thin films by RF magnetron sputtering from binary chalcogenide targets

Cu2ZnSnSe4 (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 chalcogerrides 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 Cu2Se with corresponding growth orientations of (101), (112), (220/204), (312/ 116) and (332/316). Thep-type CZTSe film grown at a substrate temperature of 150 degrees C showed a high absorption coefficient of 10(4) cm(-1) with an optical band gap of 1.56eV, resistivity as low as 1.482 Omega cm and carrier concentration of 1 x 10(19) cm(-3). These results suggested that the control of the target compositions was crucial to grow single phase and stoichiometric quaternary CZTSe films. (c) 2007 Elsevier Ltd. All rights reserved.