A study was made of As-vacancy plus Si-impurity and As-vacancy plus As-antisite complexes by using electronic techniques. It was found that the complexes exhibited metastability as a function of the position of the impurity or the antisite atom. This was similar to the behavior that was described by large lattice-relaxation models for isolated DX and EL2 centers. It was suggested that the list of metastable defects in this material would have to be extended. The results also clarified metastability mechanisms in large lattice-relaxation models. The positron states and annihilation characteristics were calculated for the defect complexes.

S.Pöykkö, M.J.Puska, M.Alatalo, R.M.Nieminen: Physical Review B, 1996, 54[11], 7909-16