The radiation response characteristics of single-and multiple-implant SIMOX (separation by implantation of oxygen) buried oxide layers that had received a supplemental oxygen implant and anneal step were measured as a function of temperature and time after exposure to short radiation pulses. A fast capacitance-voltage technique was used for these measurements. The results indicate that, in comparison to standard SIMOX, the supplemental-implant SIMOX buried oxide shows hole motion through the oxide, greatly reduced bulk hole trapping, and little or no bulk shallow electron trapping. Substantial interfacial hole trapping was observed in these materials, as well as deep electron trapping in the single-implant material. >