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 < 1800 K. We show that the diffusion law deviates from the high-temperature Arrhenius plot below T = 1200 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.