Investigation of Three‐Channel Heterostructure and High‐Electron‐Mobility Transistor with Quaternary In0.1Al0.5Ga0.4N Barrier

Herein, a high‐quality In 0.1 Al 0.5 Ga 0.4 N/GaN three‐channel (TC) heterostructure and the high‐electron‐mobility transistor (HEMT) based on it are proposed and investigated. The quaternary nitrides offer additional flexibility in adjusting the lattice constant and bandgap, enabling the achievement of a nearly strain‐free high‐Al‐content barrier. By stacking three In 0.1 Al 0.5 Ga 0.4 N/GaN heterostructures, a high 2D electron gas density of 2.59 × 10 13 cm −2 and a high electron mobility of 1707 cm 2 V −1 s −1 are achieved. As compared with the AlGaN/GaN TC heterostructure, the In 0.1 Al 0.5 Ga 0.4 N/GaN TC heterostructure reduces the sheet resistance by 39%, resulting in a 40 % reduction in the on‐resistance of the TC HEMT. Additionally, the inverse piezoelectric effect of the In 0.1 Al 0.5 Ga 0.4 N/GaN TC‐HEMT is investigated by negative‐gate voltage bias step‐stress experiments. During the stress experiments, no irreversible degradation is observed in the In 0.1 Al 0.5 Ga 0.4 N/GaN TC‐HEMT, while the AlGaN/GaN TC‐HEMT exhibits a significant deterioration beyond the critical voltage. The reliability related to the inverse piezoelectric effect of the devices can be further improved due to the lower stress in the lattice‐matched quaternary barrier.