IMPACT IONIZATION IN SILICON

The electron dynamics for electron energies up to 5 eV has been studie d by soft x-ray photoemission spectroscopy. Monte Carlo simulations ha ve been performed to derive the energy dependence of the pair-producti on rate using these results in combination with published data on the ionization coefficient and on the quantum yield for pair production. T he obtained ionization rate shows a very soft threshold at 1.2 eV, app roaching the results by Kane [Phys. Rev. 159, 624 (1967)] at higher en ergies. Several published models have been found to be inconsistent wi th the full set of experimental data we have considered.