The thermal generation of Zn-vacancy defect complexes on (110) was studied, as a function of annealing time at temperatures of between 293 and 480K, by means of scanning tunnelling microscopy. It was found that the geometrical and electronic structures, as well as the concentrations of isolated dopant atoms, P vacancies, and vacancy-Zn defect complexes were related to each other. An attractive interaction between vacancies and Zn atoms was identified. The vacancies and Zn dopant atoms could compensate each other’s charge, to form uncharged complexes. The formation of these compensated defect complexes decreased the concentration of electrically active Zn atoms. The total observable Zn concentration in the surface layers remained constant in time at temperatures of up to 415K. Only defect complexes which consisted of a surface vacancy and a sub-surface dopant atom were formed. At 480K, the observable Zn concentration decreased because defect complexes that consisted of a sub-surface vacancy and a Zn atom were formed.

P.Ebert, M.Heinrich, M.Simon, C.Domke, K.Urban, C.K.Shih, M.B.Webb, M.G.Lagally: Physical Review B, 1996, 53[8], 4580-90