Defect Annihilation by Preferential Grain Growth during Cu(In,Ga)Se2 Co-evaporation

To gain an in-depth understanding of the mechanisms and driving forces responsible for the microstructural changes during the Cu-Se deposition of the three-stage Cu(In,Ga)Se
₂
co-evaporation process and its effect on the absorber quality, we have performed a series of in-situ studies as well as complementing ex-situ studies in the recent past. Our studies provide insights into several correlating changes of the structural and physical properties of the absorber layer during Cu-Se deposition or subsequent annealing, such as defect annihilation, stress relaxation, texture changes, and grain growth. In this contribution, we combine these various observations and discuss how they can be explained by a model of abnormal grain growth, driven by differences in the defect densities of neighboring grains.