Hydrogen Diffusion in Silicon from Tight-Binding Molecular Dynamics

We present the first tight-binding molecular dynamics simulation of hydrogen diffusion in silicon for $800<T<\mathrm{}1800\mathrm{}$ K. We show that the diffusion law deviates from the high-temperature Arrhenius plot below $T=1200\mathrm{}$ K, and we compute the diffusion coefficient in a region where no experimental data are available. The diffusion mechanism and path are observed during very long simulations. We demonstrate that hydrogen diffuses through jumps, avoiding low valence-charge-density regions. Observation of jumps between non-nearest-neighbor bond-center sites is reported, and the role of the phonon spectrum of silicon is discussed.