By using 2-dimensional reciprocal-space mapping, the relative positions of the As atom (EL2 defect) which corresponded to its stable and metastable configurations were clearly established. It was shown that mere lowering of the sample temperature, before transition, induced transformation of the lattice. The characteristic temperature (120 to 140K) below which such transformation took place was the same as that for thermal recovery of the defect.

Lattice Relaxation and Metastability of the EL2 Defect in Semi-Insulating GaAs and Low Temperature GaAs G.Kowalski, S.P.Collins, M.Moore: Journal of Applied Physics, 2000, 87[8], 3663-8