The concentrations of point defects and dopant atoms were measured during the scanning tunnelling microscopy of as-grown and post-growth annealed samples of highly Si-doped material. Annealing in an As atmosphere reduced the concentration of Si atoms that was incorporated into Si pairs and clusters by cluster dissolution, while the concentrations of Si donors, Si-donor plus Ga-vacancy complexes, and Si-donor plus As-vacancy complexes increased. A Ga-vacancy mediated mechanism was proposed for the dissolution of Si clusters during heat treatment.

C.Domke, P.Ebert, K.Urban: Physical Review B, 1998, 57[8], 4482-5