Abstract: We report our recent theoretical studies on the hydrogen－induced semiconductor surface metallization observed in β－SiC(001)－3×2 surface. We show that the surface metallization arises from a novel mechanism of n－type doping of surface band via formation of hydrogen bridgebonds (i.e., Si-H-Si complex). The hydrogen strengthens the weak Si-Si dimers in the subsurface by forming hydrogen bridge bonds, and donates electron to the surface conduction band.