Hydrogen interactions with self-interstitials in silicon

We present a first-principles investigation of complexes between one or two hydrogen atoms and a Si self-interstitial (Siᵢ). The atomic structure of these complexes is a distortion of the 〈110〉 split-interstitial configuration. The (H,Siᵢ) complex has donor and acceptor levels in the band gap, both about 0.4 eV above the valence band. The (2H,Siᵢ) complex is electrically inactive, with all Si atoms bonded to four neighbors. The binding energy of H to the self-interstitial is about 2.4 eV (referenced to free atomic H). Consequences of these results for observation of self-interstitials and for processes such as point-defect condensation and dislocation nucleation are discussed.