We have studied the effect of hydrogen powerful ion beams (PIB) on the structures of GaAs and Si crystals. A "conversion" zone of a high defect concentration was formed in the near surface region. This "conversion" zone is the region where defects induced by stationary beams are escaping to the surface or annihilating at sinks. We used two direct methods of analysis: positron annihilation (PA) and Rutherford back scattering of channeled Ions (RBS/CI). Si and GaAs crystals were irradiated with 300 keV and 500 to 4800 keV beams from the modified "TONUS" and "VERA" accelerators.