New experimental findings on hot carrier transport under velocity saturation regime in Si MOSFETs

Abstract

The carrier transport properties under high field have been studied in Si MOSFETs experimentally from the following two points of view; velocity saturation and impact ionization. The electron and hole velocities in the inversion-layer were measured as a function of tangential electric field using high-resistive gate MOSFETs. It has been found that the saturation velocity is dependent on the surface carrier concentration. The impact ionization rate was studied as a parameter of the length of the pinch-off region in MOSFETs. The suppression of the ionization rate and the enhancement of anisotropic impact ionization have been simultaneously observed at 81 K in the MOSFETs with the shorter length of pinch-off region. The non-stationary transport of hot carriers in the pinch-off region is responsible for these phenomena.<>