Physical and chemical degradation behavior of sputtered aluminum doped zinc oxide layers for Cu(In,Ga)Se2 solar cells

Depth profiling showed that the increase of the potential barrier is caused by the diffusion of H2O/OH− through the grain boundaries leading to the formation of Zn(OH)2 or similar species or adsorption of species. They also indicate the presence of chloride and sulfide in the top layer and the possible presence of Zn5(OH)8Cl2·H2O and Zn4SO4(OH)6·nH2O