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, usi
ng a microRaman probe and a scanning electron microscope in combination wit
h an energy dispersive spectroscopy system (SEM-EDS). We found that for sam
ples prepared in pure nitrogen, the resulting material is basically amorpho
us material, with amorphous-GaAs with some cubic phase of As2O3 also presen
t. 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 o
f As2O3 "calculetite." SEM micrographs show the resultant morphologies obta
ined that exhibit a porous, granular, agglomerated granular appearance. EDS
and Raman suggest that the claudetite phase of As2O3 and As2O3 play a cont
ributing role in the green-blue photoluminescence emitted by spp-GaAs. (C)
2001 American Vacuum Society.