High-field drift velocity of electrons at the Si–SiO2 interface as determined by a time-of-flight technique

Abstract

We describe a new technique for the study of high-field transport at semiconductor–insulator interfaces. In this technique, we observe the time-of-flight of discrete charge packets introduced by a pulsed laser. The packets drift in a region of uniform applied tangential field at the interface. We present data on the room temperature drift velocity of electrons at the interface between (100) silicon and thermally grown silicon dioxide as a function of both tangential and normal electric fields. We observe velocities near saturation of 8.9×106 cm/s at a tangential field of 4 V/μm and a normal field of 9 V/μm, and extrapolate to a saturation velocity of 9.2×106 cm/s independent of normal field. This value is more than 40% higher than reported by early workers, and is close to the saturation velocity observed in bulk silicon.