PRESSURE-DEPENDENCE OF DEEP LEVELS OF THE AS ANTISITE, THE GA-VACANCYAS-INTERSTITIAL PAIR, AND OF THE STABLE AND METASTABLE STATES OF EL2

We report density-functional theory calculations of the tetrahedral, i solated arsenic antisite (As(Ga)) in GaAs and of its metastable struct ure, the gallium-vacancy-arsenic-interstitial pair (V(Ga)As(i)). In or der to determine the pressure dependence of the defect levels, the sel f-consistent Green-function method is applied. The calculated results are in agreement with experimental data on the stable and metastable s tates of EL2. This implies that the stable state of EL2 is indeed well described by the properties of the isolated As antisite. Furthermore, the results support the identification of the metastable state of EL2 with the V(Ga)As(i) pair and identify the symmetry of the pressure-in duced defect level.