Impact ionization rate near thresholds in Si

Abstract

The impact ionization rate in Si is determined by performing the full-band Monte Carlo simulations with an ionization model that takes into account the correct joint density of states of Si. The ionization model, which is a refined version of the previously reported one [N. Sano, M. Tomizawa, and A. Yoshii, Jpn. J. Appl. Phys. 30, 3662 (1991)], features a finer mesh spacing for discretizing the wave-vector space and a smaller energy interval for the energy-conserving δ function in the transition probability. The impact ionization rate shows significant anisotropy near thresholds (≤3 eV) associated with the complexity of the indirect band structure in Si. When the impact ionization rate is averaged over all directions, good agreement with that extracted from recent experiments [E. Cartier, M. V. Fischetti, E. A. Eklund, and F. R. McFeely, Appl. Phys. Lett. 62, 3339 (1993)] is obtained.