AbstractThe structure of As implanted GaAs layers before and after annealing are described and the relation between the structural quality and carrier lifetime was determined. Subpicosecond carrier lifetimes were found already for as-implanted layers, and this value changes only slightly after annealing in the temperature range up to 600°C. Annealing of As-implanted layers leads to the growth of As precipitates with a similar orientation relationship as those observed in low-temperature MBE-grown GaAs layers. However, it is still not clear whether point defects created by implantation or the As precipitates are responsible for the short carrier lifetime.