Investigation of defects in high-energy heavy ion implanted GaAs

Undoped semi-insulating GaAs were implanted with 500 MeV Ne ions. Monte Carlo simulation revealed that the largest concentration of vacancies induced was around the end of the Ne ion range. Positron Annihilation measurement showed that after lower dose implantation, divacancies were formed, which coexisted with monovacancies. On increasing the dose, all the monovacancies changed to divacancies. The temperature dependence of positron lifetime suggested the existence of negatively charged antisites GaAs. Near infra-red spectra were also measured to study the implantation induced amorphous layers.