Interface Charge Effects on 2-D Electron Gas in Vertical-Scaled Ultrathin-Barrier AlGaN/GaN Heterostructure

The combination of ultrathin-barrier (UTB) AlGaN ( x grown by low-pressure chemical vapor deposition (LPCVD) is a promising technique for development of GaN-based millimeter-wave power amplifiers and recess-free enhancement-mode (E-mode) power switches. The LPCVD-SiN x passivation is capable of inducing high density of positive charges at the SiN x /(Al)GaN interface ( $\sim 3.50 \times 10^{13}$ cm−2), ensuring efficient recovery of 2-D electron gas (2-DEG) density that is comparable with conventional AlGaN/GaN heterostructure. Temperature-dependent Hall measurements and scattering mechanism simulations confirm the positive interfacial charges as well as interface states with density below 1013 cm−2 and exert weak remote coulombic scattering of 2-DEG in metal–insulator–semiconductor heterojunction field-effect transistors (MIS-HFETs), which warrants a low ON-resistance of UTB-AlGaN/GaN-based devices. UTB-AlGaN ( x passivation is a compelling technology platform for fabrication of high-frequency power amplifiers and high-efficiency E-mode power switches.