The formation of amorphous layers in GaAs during ion bombardment at elevated temperatures, where dynamic annealing of radiation-induced defects is substantial, is shown to be extremely sensitive to the implantation temperature. For example, we have found that a temperature change of only 6 °C can change the residual damage from small clusters barely visible by conventional transmission electron microscopy and Rutherford backscattering to a thick amorphous layer. The temperature at which this occurs is strongly dependent upon the ion flux. ©1997 American Institute of Physics.