Analysis of Improved 2D Electron Gas Mobility in InAlN/AlN/InGaN High‐Electron‐Mobility Transistors with GaN Interlayer

Abstract

Herein, the physical mechanism of the GaN interlayer for improving 2D electron gas (2DEG) mobility in the InGaN channel using an intersub‐band scattering model is systematically elucidated. The model takes into account various scattering mechanisms between the first four sub‐bands, in which the wavefunction of each sub‐band is obtained by self‐consistently solving 1D Schrödinger−Poisson equations. The total 2DEG mobility is obtained by averaging the sub‐band mobility by the percentage of electrons in the different sub‐bands. The effect of introducing different thicknesses of the GaN interlayer on the mobility limited by various scattering mechanisms is discussed in detail, especially polar optical phonon scattering and alloy disorder scattering. The calculated results are well supported by the reported experimental data, validating the correctness of the model.

Multi‐Subband Polar Optical Phonon Scattering in InAlN/AlN/GaN Heterostructures

“…For instance, a simplified multi-subband POP scattering model replaces the second square bracket in Equation ( 8) with ð1 À cos θÞ to simplify the contribution from in-scattering processes, resulting in a closed-form momentum relaxation time. [12][13][14][15] The frequently used single-subband POP scattering uses the quantum limit approximation, which assumes that only the lowest subband is occupied by electrons and ignores the impact of higher subbands occupation on electron transport. [9][10][11] The validity of the two simplified models will be evaluated.…”

“…[9][10][11] Other studies simplified the in-scattering processes to avoid the iterative numerical calculation process. [12][13][14][15] Others used approximate analytic expressions for mobility to describe the POP scattering. [16][17][18] The predictions of these simplified models often differ greatly.…”

Nanoscale Stress Localization Effects on the Radiation Susceptibility of GaN High‐Mobility Transistors

“…Such unique channel characteristics give rise to low on-resistance and high-frequency behavior without any intentional doping. [2,3] Due to their wide bandgap, high critical field, and good saturation velocity, GaN HEMTs are more attractive for highfrequency, high-power applications. [3,4] High threshold energy (E d ) for atomic displacement, [5] dynamic annealing of point defects, [6] and absence of a conventional gate insulator [7] make them attractive in radiation environment as well.…”