Identification of the 0.82-eV Electron Trap,EL2in GaAs, as an Isolated Antisite Arsenic Defect

$\mathrm{EL}2\mathrm{}$ is a technologically important deep level in GaAs whose identification has been the subject of intense study. In this paper we present uniaxial stress and magnetic field experiments which establish for the first time that $\mathrm{EL}2\mathrm{}$ has tetrahedral symmetry and is, therefore, an isolated point defect. Combining this result with earlier data, we conclude that $\mathrm{EL}2\mathrm{}$ is an isolated arsenic antisite defect.