Threshold energy and impact ionization scattering rate calculations for strained silicon

摘要

In this work, a comprehensive method to obtain the impact ionization rate has been developed and applied to both strained and unstrained silicon. Special care was taken to find criteria which support the appropriateness of our choice of numerical methods, especially the integration method and the delta distribution approximation. The algorithm developed takes into account both efficiency and accuracy requirements. We investigate the impact of introducing stress on the impact ionization rate and observe that the impact ionization threshold is shifted to lower energies, but by a smaller amount than the band gap is lowered. This can be explained by the availability of fewer possibilities to satisfy both energy and momentum conservation conditions at the same time.