Stacking fault effects in pure and n-type doped GaAs

Using ab initio total-energy calculations, we investigate the effects of st acking faults on the properties of dopants in pure and n-type doped GaAs. W e find that the Si impurity segregates towards a GaAs stacking fault. A Si atom at a Ga site in the stacking fault, in either a neutral or a negative charge state, is energetically favorable as compared to a Si atom at a Ga s ite in a crystalline environment by as much as 0.2 eV. We also find that a Si impurity in the stacking fault cannot occupy metastable positions, as oc curs in the formation of DX centers. Thus, stacking faults can prevent the formation of DX-like centers in GaAs. (C) 2001 American Institute of Physic s.