It was recalled that, although it was widely accepted that EL2 was an As antisite, the identity of its metastable state, EL2*, had not been confirmed by experiment. It was suggested here that cross-sectional scanning tunnelling microscopy could be used to identify EL2*. The concept was based upon a comprehensive first-principles total-energy study of surface-defect metastability. This revealed rich structures for EL2* near to the surface. The energy difference between EL2* and EL2 could be reduced to only one tenth of that due to interaction with relaxed surface atoms.

Defect Metastability in Surfaces - a Study of EL2 Defects in GaAs(110) S.B.Zhang: Physical Review B, 1999, 60[7], 4462-5