The implantation of 2MeV Si and 3MeV Zn and Ga ions, and subsequent annealing, were used to eliminate threading dislocations from 3-thick GaAs on Si. For annealing temperatures of 600 to 1000C, it was found that Si implantation was most effective in reducing the number of threading dislocations in the near-surface region where excess vacancies were created by implantation. This suggested that dislocations disappeared by absorbing vacancies. However, no appreciable reduction in the number of dislocations was observed in the case of Zn and Ga implantation; especially for annealing temperatures above 800C. However, at temperatures below 700C the dislocations in the surface region were clearly reduced in number when compared with those in a non-implanted sample. Such differing effects upon dislocation behavior were attributed to a difference in the movement of these impurities towards the surface during annealing. In the case of Si implantation, the bending of dislocations that were parallel to the interface between a film and a substrate was observed. This was due to an increased lattice friction in highly Si-doped regions.

M.Tamura, T.Saitoh: Japanese Journal of Applied Physics, 1995, 34[II-9B], L1194-7