A MULTIBAND MODEL FOR HOLE TRANSPORT IN SILICON AT HIGH-ENERGIES

A new microscopic silicon model for hole transport at high electric fi elds featuring two valence bands in a finite Brillouin zone is present ed. The band parameters and the electron-phonon coupling constants wer e determined by best fitting the density of states and the experimenta l and theoretical results for transport properties in the low and inte rmediate field-strength range. Hole impact ionization has been introdu ced following a new scheme that goes beyond the limitations contained in the Keldysh formula. The present model, coupled to an analogous mod el already developed for electrons, allows study of bipolar transport in silicon devices. Applications to bulk Si and Si p-MOSFETs are prese nted.