The TCAD Simulation Study of m-GaN Based HEMTs by Using $\varepsilon-\text{Ga}_{2}\mathrm{O}_{3}$ as Barriers for High Frequency Application

High electron mobility transistors (HEMTs) based on $\varepsilon-\text{Ga}_{2}\mathrm{O}_{3}/\mathrm{m}$ -face GaN heterojunction is reported for high frequency devices by TCAD simulation study. A very high two-dimensional electron gas (2DEG) density of up to $10^{14}\text{cm}^{-2}$ has been obtained at the interface of $\varepsilon-\text{Ga}_{2}\mathrm{O}_{3}$ and m-surface $\text{GaN}$ due to the high spontaneous polarization of $\varepsilon-\text{Ga}_{2}\mathrm{O}_{3}$ . The characteristics of HEMTs are studied with a depletion mode, showing a very high saturation current. The influence of Schottky gate regulation on channel carriers with different $\varepsilon-\text{Ga}_{2}\mathrm{O}_{3}$ barrier thickness has been researched. Small signal simulation results show that the peak current gain cutoff frequency $(\mathrm{f}_{\mathrm{t}})$ of 168 GHz and peak power gain cutoff frequency $(\mathrm{f}_{\max})$ of 500 GHz have been obtained, indicating that the device has excellent high frequency performance. Meanwhile, the effect of gate passivation layer on the frequency characteristics of the device is studied by analyzing the parasitic capacitance. Therefore, the results can provide theoretical guidance for the potential application of $\varepsilon-\text{Ga}_{2}\mathrm{O}_{3}$ /m-GaN HEMTs in radio-frequency devices.