Undoped semi-insulating specimens were implanted with 500MeV Ne ions. Monte Carlo simulations revealed that the highest concentrations of vacancies which were introduced were located around the end of the Ne ion range. Positron annihilation measurements showed that, after lower-dose implantation, divacancies were formed that co-existed with monovacancies. Upon increasing the dose, all of the monovacancies changed to divacancies. The temperature dependence of the positron lifetime suggested the existence of negatively charged antisites, GaAs.

Investigation of Defects in High-Energy Heavy Ion Implanted GaAs Z.Q.Chen, Z.Wang, S.J.Wang, M.D.Hou: Applied Radiation and Isotopes, 2000, 52[1], 39-45