Assessment of T-Gate and Π-Gate HEMT Through Cellular Monte Carlo Simulations

Several different ${T}$ and $\Pi $ -gate architectures of GaN/AlGaN high electron mobility transistor (HEMT) are compared using full band cellular Monte Carlo (CMC) device simulator for device performance (dc and RF) while accounting for self-heating modeled through energy balance equation (EBE) for acoustic and optical phonons which self consistently couple charge and heat transport. Efficacy of $\Pi $ -gate over ${T}$ –gate is assessed for suppression of hot electron under device self-heating obtained through solution of electron energy distribution function (EDF) from complete nonlinear Boltzmann transport equation (BTE). The $\Pi $ -gate suppresses 19.75% more hot electrons corresponding to a dc power of 2.493 W/mm for ${V}_{\text {gs}}$ = −0.6 V (max transconductance). For the dc performance, ${I}_{\text {ds}}$ is nearly the same for each device configuration over the entire bias range, whereas, for the RF performance the current gain was evaluated over a frequency range 20–120 GHz in each device for both thermal (including self-heating) and isothermal (without self-heating). The evaluated cut off frequency is around 7% lower for the thermal case than the isothermal case, and for the experimentally characterized ${T}$ -gate device, and for the simulated cutoff frequency closely follows the experimental measurement.