High-field drift velocity of electrons in silicon inversion layers

Abstract

The dependence of the drift velocity on electric field for electrons in n-type silicon inversion layers is determined from the d.c. drain-conductance measurement of polysilicon resistive-gate field-effect-transistors. Up to fields 1.5 × 10 4 V/cm this dependence is well approximated by an empirical relationship which satisfies Thornber's theory. The extrapolated saturation drift velocity, nearly independent of normal (or gate) electric fields up to 8 × 10 5 V/cm, is 6.0 × 10 6 cm/s. This value is used in a field-dependent model for electron mobility in silicon inversion layers implemented in a 2-D device simulator. Accurate numerical simulations of the resistive-gate device correctly predict the experimentally observed drain current-drain voltage characteristics.