New avalanche breakdown model for nonuniform electric fields

It is shown that correct avalanche breakdown voltages for submicron MESFETs and especially for HEMTs can be obtained only if we substitute the phenomenological avalanche coefficients dependencies on electric field magnitude with the similar dependencies of these coefficients on the mean energies of electron and hole gases. The same substitution for other kinetic coefficients is usual in so called temperature models used for simulation systems with nonuniform electric fields. Application of new model for MESFET simulation leads to noticeable improvement of measured and simulated breakdown voltages coincidence and in HEMT simulation one can obtain sensible results for current-voltage characteristics only with the help of the new model. The new model success is based on more physically meaningful operation with the great contact electric fields which are common in submicron gate MESFETs and HEMTs