Comparative Study of Variations in Gate Oxide Material of a Novel Underlap DG MOS-HEMT for Analog/RF and High Power Applications

In this paper an Underlap Double Gate (U-DG) Symmetric Heterojunction AlGaN/GaN Metal Oxide Semiconductor High Electron Mobility Transistor (MOS-HEMT) with gate oxide materials of different dielectric constant has been studied using gate oxide materials such as Hafnium dioxide (HfO2), Silicon dioxide (SiO2) and a symmetric gate stack (GS) of HfO2-SiO2. In this work, the analog performance of the devices has been studied on the basis of parameters like transconductance (gm), transconductance generation factor (gm/ID) and intrinsic gain (gmR0). This paper depicts the effect of varying oxide materials on the analog and RF figure of merits (FOMs) such as the gate to drain capacitance (CGD), gate to source capacitance (CGS) and total gate capacitance (CGG), intrinsic resistances, cut-off frequency (fT) and maximum frequency of oscillation (fMAX) using non-quasi-static approach. Studies show that the introduction of a gate oxide layer in the MOS-HEMT device increases the gate controllability reducing gate leakage currents improving RF performance. U-DG AlGaN/GaN MOS-HEMT with HfO2 gate dielectric shows superior Power output efficiency (POE) of 55% compared to the HfO2-SiO2 composite structure and SiO2 with 26% and 20% respectively.