THRESHOLD BEHAVIOR IN BACKGATING IN GAAS METAL-SEMICONDUCTOR FIELD-EFFECT TRANSISTORS - INDUCED BY LIMITATION OF CHANNEL-SUBSTRATE JUNCTIONTO LEAKAGE CURRENT

An analytical model is proposed to understand backgating in GaAs metal -semiconductor field-effect transistors (MESFETs), in which the effect of channel-substrate (CS) junction is included. We have found that th e limitation of CS junction to leakage current will cause backgate vol tage to apply directly to CS junction and result in a threshold behavi or in backgating effect. A new and valuable expression for the thresho ld voltage has been obtained. The corresponding threshold electric hel d is estimated to be in the range of 1000-4000 V/cm and for the first time is in good agreement with reported experimental data. More, the e liminated backgating effect in MESFETs that are fabricated on the GaAs epitaxial layer grown at low temperature is well explained by our the ory. (C) 1997 American Institute of Physics.