A new bistable VAs-impurity defect was discovered in epitaxial layers which had been grown by using the metalorganic chemical vapor deposition method. The parameters of this defect in the stable state were identical to those of the E1 defect which formed during irradiation. During irradiation of the layers, the transformation mechanism changed. This was related to the formation of another pair: VAs-Asi. After the irradiation of epitaxial layers with 1MeV electrons, a ten-fold increase in the concentration of metastable defects was found. The existence of VAs in these pairs appeared to determine the proximity of the defect parameters in the stable state to those of the radiation E1 level. Changes in the thermal activation energy and the capture cross-section were suggested to be related to the differing strengths of Coulomb interaction among the pair components.

M.M.Sobolev, I.V.Kochnev, M.I.Papentsev, V.S.Kalinovsky: Materials Science Forum, 1995, 196-201, 1097-102