Current oscillation in GaN-HEMTs with p-GaN islands buried layer for terahertz applications

A GaN-based high electron mobility transistor (HEMT) with p-GaN islands buried layer (PIBL) for terahertz applications is proposed. The introduction of a p-GaN island redistributes the electric field in the gate–drain channel region, thereby promoting the formation of electronic domains in the two-dimensional electron gas (2DEG) channel. The formation and regulation mechanism of the electronic domains in the device are investigated using Silvaco-TCAD software. Simulation results show that the 0.2 μm gate HEMT with a PIBL structure having a p-GaN island doping concentration ( N p ) of 2.5 × 10 18 cm −3 –3 × 10 18 cm −3 can generate stable oscillations up to 344 GHz–400 GHz under the gate–source voltage ( V gs ) of 0.6 V. As the distance ( D p ) between the p-GaN island and the heterojunction interface increases from 5 nm to 15 nm, the fundamental frequency decreases from 377 GHz to 344 GHz, as well as the ratio of oscillation current amplitude of the fundamental component to the average component I f / I avg ranging from 2.4% to 3.84%.