A study on mechanisms of Sb-doping induced grain growth for Cu(InGa)Se2 absorbers deposited from quaternary targets

In order to investigate the effects of Sb-doping induced grain growth of Cu(InGa)Se2 (CIGS) films processed from quaternary target, thin metallic Sb layers have been deposited in the bottom, in the middle and on the top of CIGS layer, respectively. The effects of temperature on Sb-doped CIGS grain size are explored. These results demonstrate that the incorporated Sb in the bottom and middle of CIGS films could significantly increase the grain size of films at selenization temperature of 500 °C, while the incorporated Sb on the top of CIGS takes little effect on grain growth. The phase and morphology variation of metallic Sb and the phase evolution of Sb-doped Mo-CIGS interface with selenization temperature are investigated. These results suggest that the metallic Sb might be selenized into Sb2Se3. As soon as Sb2Se3 generates, it might decompose into volatile phases at 500 °C. In the migration of these volatile phases through CIGS films, the grain growth is enhanced.