Field and thermionic‐field transport in GaAs/AlGaAs/GaAs heterojunction barriers

Abstract

This paper considers the transport of conduction band electrons as a result of tunneling through a triangular potential barrier fabricated within a GaAs/Al x Ga 1-x As/GaAs heterojunction. The triangular barrier was formed by the composition grading of the Al x Ga 1-x As region from x = 0 to x = 0.3, which forms part of a cathode emitter in a commercial Gunn diode. The experimental data for the current -voltage characteristics obtained for a range of temperatures from 77 to 273 K were used to test a simplified thermionic-field model. Good agreement has been obtained between theory and experiment, thus confirming the usefulness of this simple model for device evaluation. The comparison of the data over the experimental temperature range shows that the thermionic-field emission observed at 273 K gives way to field emission at 77 K. This is a result of the removal of the more energetic electrons in the conduction band at lower temperatures.