The microstructure of Cu(In,Ga)S2 solar cell absorber films prepared using three-stage and two-stage evaporation

The microstructure of three-stage Cu-poor Cu(In,Ga)S2 solar cell absorbers has been compared with that of two-stage Cu-rich absorbers using high-resolution Transmission Electron Microscopy. It was found that the grains from three-stage evaporation have more stacking faults, and most of the grain boundaries are irregular, such as sawtooth shaped. The grains from two-stage evaporation have less defects, and the grain boundaries are straight. The difference of growth mechanisms between three-stage and two-stage evaporation are discussed and compared to the case of Cu(In,Ga)Se2.