Metastability of two-hydrogen complexes in silicon

A two-hydrogen interstitial complex (H-2(**)) in crystalline Si that exhibits metastability is proposed via first-principles total energy calculations. In its most stable state, H-2(**) is 0.28 eV/H higher in energy than H-2(*) and is electron-spin-resonance inactive. The complex has a metastable spin active state arising from a Si dangling-bond in which the H-H separation is 2.39 Angstrom. The properties of H-2(**) make it a promising candidate for the defect responsible for the Staebler-Wronski effect in amorphous Si. (C) 2003 American Institute of Physics.