An investigation was made of  the hole effective mass, intrinsic defects and group VI-A impurities in γ-CuI by first-principles calculations. It was found that the hole effective mass of γ-CuI was light, in line with the high p-type mobility observed in experiments. The p-type conductance was expected to originate from Cu vacancies, which have a low formation energy with no significant n-type compensating defects. The relative high transition level of Cu vacancy, however, may lead to a low hole concentration in the γ-CuI sample. Additionally, no shallow transition levels were found in γ-CuI with substitutional group VI-A impurities at I sites.

First-Principles Study of γ-CuI for p-Type Transparent Conducting Materials. D.Huang, Y.J.Zhao, S.Li, C.S.Li, J.J.Nie, X.H.Cai, C.M.Yao: Journal of Physics D, 2012, 45[14], 145102