Existing data on then–ptype conversion of semi‐insulating GaAs during high temperature (1100–1200 °C) anneals are fit using a previously developed model in which EL2 is identified as the native defect AsGaVGa. In this model EL2 dissociates into the acceptor VGaand the donor AsGa. The latter defect then rapidly captures a divacancy to form the electrically neutral complex AsGaVAsVGa. The decrease in EL2 concentration, then–ptype conversion of GaAs, and the subsequent increase in hole concentration as the annealing temperature is increased are correlated in the model. ©1995 American Institute of Physics.