We have analyzed spark-processed porous GaAs (spp-GaAs) samples prepared by the application of high-voltage discharges at low repetition rates (20 Hz) in different ambients, ranging from pure nitrogen to pure oxygen flow, using a microRaman probe and a scanning electron microscope in combination with an energy dispersive spectroscopy system (SEM-EDS). We found that for samples prepared in pure nitrogen, the resulting material is basically amorphous material, with amorphous-GaAs with some cubic phase of As2O3 also present. For samples prepared under even a low concentration of oxygen, 20:1, we find that the cubic phase of As2O3 is substituted by the monoclinic phase of As2O3 “claudetite.” SEM micrographs show the resultant morphologies obtained that exhibit a porous, granular, agglomerated granular appearance. EDS and Raman suggest that the claudetite phase of As2O3 and As2O5 play a contributing role in the green-blue photoluminescence emitted by spp-GaAs. © 2001 American Vacuum Society.