The formation and annihilation of hydrogen (H)-related complexes were investigated in boron (B)- or phosphorus (P)-doped Si treated with high concentration of atomic H. The passivation and reactivation process of dopant carriers were significantly different between the p-type and n-type specimens. The differences are explained by the stable sites of the H atoms in the p-type and n-type specimens and, in turn, by the formation of H-related defects: i.e., H multiple trapping centers are formed by bond-breaking due to H atoms only in p-type B-doped Si. The formation of such defects retards the reactivation of B dopants by annealing. (C) 2007 Elsevier B.V. All rights reserved.