A STUDY _ OF MESFET TRANSCONDUCTANCE BY USING LINEARLY GRADED SUBSTRATE-CHANNEL JUNCTION. MODEL

Abstract

Previously channel-substrate junction in ion-implanted MESFET was assumed to be abrupt junction. With the assumption of abrupt junction many expressions for useful quantities like threshold voltage and transonductance have already been given. But in reality, the assumption of abrupt junction. is not true and channel-substrate junction in ion implanted MESFET is linearly graded junction. The expression for threshold voltage considering linearly graded junction gives nearly same result as experimental results available in literature. In present work using this accurate threshold voltage expression, transconductance (gm) of the MESFET has been calculated. It has been compared with previous existing curves. Further, transconductance (g;n) has been calculated by varying important parameters viz, temperature, implantation energy, cap layer thickness, substrate bias voltage and doping concentration etc. Finally the effect of these variations on transconductance has been discussed.