Transport Properties of InGaN Channel-Based Heterostructures with GaN Interlayers

To systematically investigate the effect of GaN interlayers (IL) on electron transport properties of GaN-based heterostructures, three groups of heterostructures, AlInN/AlN/GaN/InGaN/GaN, AlInN/GaN/AlN/InGaN/GaN and AlInN/AlGaN/GaN/InGaN/GaN were compared in this study, noted as AlN-IL first, GaN-IL first and AlGaN-IL first, respectively. The conduction band diagram and electron density were simulated with a numerical method, and the mobility was calculated analytically with seven scattering mechanisms. Compared with the heterostructure without GaN-IL, an increased thickness of GaN-IL leads to a greater dispersion of electrons into the upper GaN channel. Consequently, the density and mobility of the two-dimensional electron gas (2DEG) result from combined contributions from both the upper GaN and lower InGaN channels. After analyzing the scattering mechanism and electron distribution probability in each channel, the study explores variations in GaN-IL thickness, temperature, and alloy composition in AlGaN IL. The results show that almost all mobilities are enhanced with the incorporation of GaN-IL even at an elevated temperature of 1000 K, especially for AlN-IL first and AlGaN-IL first structure. The mobility of all heterostructures in the GaN channel is primarily reduced by alloy composition fluctuation scattering and polar optical phonon scattering. Conversely, alloy disorder scattering and polar optical phonon scattering should be minimized in the InGaN channel.