The UV/mm-wave technique composed of ultraviolet photoexcitation and millimeter wave probe was examined with photoconductivity amplitude (PCA) to characterize the slight subsurface damage induced by implanting H2
+ ion into the subsurface at sub micron depth of Si wafers. The identical samples were also characterized using pulse photoconductivity amplitude (PPCA) obtained by another technique which is specified by blue laser photoexcitation and microwave probe. PCA decreased with increase of ion dose, which coincided well with the result in PPCA. PPCA decreased with increase of implantation energy as 90 to 120 keV, but PCA increased at 120keV. Both PCA and PPCA well reflected the damage at sub micron depth. PCA reflected damage in shallower depth compared to PPCA.