Nonstoichiometric GaAs obtained by implantation with 2 MeV arsenic ions at 1015cm−2dose is studied. As‐implanted samples show a <200 fs lifetime of photocarriers and low resistivity due to hopping, with mobility less than 1 cm2/V s. Annealing of the samples at 600 °C leads to substantial recovery of postimplant damage, as seen from Rutherford backscattering channeling spectra and mobility increase to about 2000 cm2/V s, but photocarrier lifetime is still about 1 ps. These parameters are similar to those of low‐temperature GaAs annealed at 600 °C, and make arsenic implanted GaAs an interesting material for optoelectronic applications. ©1995 American Institute of Physics.