DIRECT OBSERVATION OF THE DRIFT VELOCITY AS A FUNCTION OF THE ELECTRIC FIELD IN GALLIUM ARSENIDE

Abstract

The drift velocity as a function of the electric field in gallium arsenide was measured directly by studying the response of a reverse-biased Schottky-barrier i-n+ GaAs photodetector to a step input of light. The photoresponse was dominated by trapping of electrons in the i region. Analysis based on a simple model yielded the drift velocity—electric field characteristic in GaAs up to fields of 9000 V/cm. A region of negative differential mobility was observed to exist between a peak field of 2200 V/cm and an apparent valley field of 8000 V/cm.