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 (${\mathrm{Si}}_{\mathit{i}}$). The atomic structure of these complexes is a distortion of the 〈110〉 split-interstitial configuration. The (H,${\mathrm{Si}}_{\mathit{i}}$) complex has donor and acceptor levels in the band gap, both about 0.4 eV above the valence band. The (2H,${\mathrm{Si}}_{\mathit{i}}$) 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.