Assessment of intrinsic small signal parameters of submicron SiC MESFETs

In this paper, a technique has been developed to estimate intrinsic small signal parameters of submicron SiC MESFETs, designed for high power microwave applications. In the developed technique, small signal parameters are extracted by involving drain-to-source current, Ids instead of Schottky barrier depletion layer expression. It has been demonstrated that in SiC MESFETs, the depletion layer gets modified due to intense transverse electric field and/or self-heating effects, which are conventionally not taken into account. Thus, assessment of AC small signal parameters by employing depletion layer expression loses its accuracy for devices meant for high power applications. A set of expressions for AC small signal elements has been developed using Ids and its dependence on device biasing has been discussed. The validity of the proposed technique has been demonstrated using experimental data.