The generation of defects in buried oxide layers in silicon-on-insulator structures by vacuum ultraviolet radiation is studied using electron/hole trapping measurements and electron spin resonance. The oxide layers produced by oxygen implantation show trap generation near the irradiated oxide surface, in contrast to thermally grown and bonded oxides, in which the defects are produced over the entire oxide volume. Spatially confined trap production is associated with the limited length of radiolytic hydrogen diffusion in the oxide during irradiation due to the enhanced interaction of hydrogen with the oxide network.