Extended Anti-Site Defects in Tetrahedrally Bonded Semiconductors

Typically point defects are modeled by adding, removing, or exchanging at most few atoms around a given lattice site. We demonstrate the possibility of formation of extended antisite defects that involve complex, nonlocal atomic rearrangements, which cannot be captured within a simple point defect model. We illustrate the formation of extended antisite defects in Cu2SnS3 and Cu2SnZnS4 solar absorbers where they lower the formation energy by up to about 1 eV per defect. These extended antisite configurations can dramatically change the stoichiometries and doping properties of multinary semiconductors that have a propensity towards disorder.