EFFECTS OF INTERFACE STATES ON SUBMICRON GAAS METAL-SEMICONDUCTOR FIELD-EFFECT TRANSISTORS ASSESSED BY GATE LEAKAGE CURRENT

The effects of the interfacial oxide layer in Schottky barrier junctio ns on submicron GaAs metal-semiconductor field-effect transistors (MES FETs) have been investigated. These effects include a shift in thresho ld voltage and compression in transconductance which can be explained by the current transport theory for the Schottky barrier with an inter facial layer. MESFETs were characterized by direct current measurement s and oxide-related degradation was evaluated by measuring the gate le akage current. It has been shown that a gate-length dependent study of threshold voltage and transconductance is only possible if all the de vices under consideration have identical Schottky responses. The curre nt through a Schottky barrier appears to flow in a voltage-dependent r esistor and the voltage drop across this resistor cannot be neglected when the density of states at the metal-semiconductor interface become s prominent because it will effectively increase the threshold voltage and reduce the device gain. (C) 1995 American Vacuum Society.