A physics-based modeling method for DC characteristics of GaN HEMTs with conventional, dual-, and tri-gate

Abstract In this study, we have developed a physics-based modeling approach to accurately characterize the DC properties of GaN high electron mobility transistors (HEMTs) featuring conventional, dual-, and tri-gate architectures. Our methodology begins with the derivation of analytical expressions for the intrinsic drain current of these three device types, omitting the effects of source and drain access resistances. For dual-gate HEMTs, we employ an approximation of depletion within a rectangular region to depict the channel modulation achieved by the sidewall gate. Building upon this, we dissect the combined influence of the top and sidewall gates in tri-gate HEMTs into two distinct control mechanisms. This involves initially calculating the two-dimensional electron gas (2DEG) density under sole top gate control, followed by determining the 2DEG depletion width governed by the sidewall gate. Incorporating access resistances, the DC characteristics of all three devices are computed through numerical iteration. To validate the channel control model directly, we exclude the self-heating effect and conduct comparative TCAD simulations. Furthermore, our modeling results, which encompass the self-heating effect, are corroborated by experimental data, thereby ensuring the reliability and accuracy of our approach.