Combined effects of high-energy Si, Zn and Ga ion implantation and annealing on the reduction of threading dislocations in GaAs on Si

Implantation of 2 MeV Si, and 3 MeV Zn and Ga ions and annealing have been adapted in order to eliminate threading dislocations in 3-μm-thick GaAs on Si. Si ion implantation is most effective for reducing threading dislocations over an annealing temperature range from 600 to 1000°C in the near-surface region where excess vacancies are created by implantation, suggesting that dislocations disappear by absorbing vacancies. However, no appreciable reduction of dislocations is observed in the case of Zn and Ga implantation, especially for annealing temperatures higher than 800°C, although at temperatures lower than 700°C, the dislocations in the surface region are clearly reduced, compared with those in a no-implantation sample. Such different effects on dislocation behavior are attributed to a different movement of these impurities toward the surface during annealing. Also, in Si implantation, the bending of dislocations parallel to the interface between a film and substrate is observed due to increased lattice friction in a highly Si-doped region.