Role of anion–cation antisites in Zn-based II–IV–V2 chalcopyrite semiconductors

Abstract

Since the order–disorder phase transition easily occurs during the growth of optoelectronic II–IV–V2 ternary compounds, cation–cation antisites were always considered as the major point defects, while anion-related defects did not attract sufficient attention. In this paper, based on first-principles simulations, the anion–cation antisites are revealed to be comparable to or even dominate over the cation–cation antisites in II–IV–V2 phosphides and arsenides. These antisite defects are predicted to have significant impacts on the optoelectronic properties because they can either act as nonradiative recombination centers or enhance the p-type carrier concentration. Furthermore, based on the calculated defect properties and band alignments, we propose that the alloy ZnGe(P,As)2 can be an efficient p-type solar cell absorber. Its maximal open circuit voltage is effectively enlarged by the low valence band edge; meanwhile, the dominating anion–cation antisites are electrically benign. These results highlight the necessity of considering the anion–cation antisites in the defect engineering of II–IV–V2 phosphides and arsenides.