Need for an acceptor level in the As sub(Ga) - As sub i model for EL2.

The interacting arsenic-antisite arsenic-interstitial model for the structure of EL2 (a native metastable defect in GaAs) has been analyzed using Greens function calculations of the level structure and total energy, and where available, the experimental energies. A mechanism for photoexcitation to the metastable state has been identified. Although the model is satisfactory in many ways, our analysis indicates need for an acceptor level in the range of 0.2 0.5 eV above the main donor level. Such a level has not yet been seen.