The radiation damage introduced inn-GaAs by 4-MeV N+implantation at a dose of1×1015cm−2has been analyzed using micro-Raman spectroscopy. Implantation followed by annealing at 600 °C was found to produce a strongly compensated near-surface layer possessing a high crystalline quality. At the same time a pronounced disorder was found underneath the high-resistance layer which enables the fabrication of 2.5-&mgr;m thick free-standing membranes using selective electrochemical etching techniques.©1997 American Institute of Physics.