The mobility of two-dimensional electron gas in AlGaN/GaN heterostructures with varied Al content

Abstract

The mobility of the two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructures changes significantly with Al content in the AlGaN barrier layer, while few mechanism analyses focus on it. Theoretical calculation and analysis of the 2DEG mobility in AlGaN/GaN heterostructures with varied Al content are carried out based on the recently reported experimental data. The 2DEG mobility is modeled analytically as the total effects of the scattering mechanisms including acoustic deformation-potential, piezoelectric, polar optic phonon, alloy disorder, interface roughness, dislocation and remote modulation doping scattering. We show that the increase of the 2DEG density, caused by the ascension of the Al content in the barrier layer, is a dominant factor that leads to the changes of the individual scattering processes. The change of the 2DEG mobility with Al content are mainly determined by the interface roughness scattering and the alloy disorder scattering at 77 K, and the polar optic phonon scattering and the interface roughness scattering at the room temperature. The calculated function of the interface roughness parameters on the Al content shows that the stress caused AlGaN/GaN interface degradation at higher Al content is an important factor in the limitation of the interface roughness scattering on the 2DEG mobility in AlGaN/GaN heterostructures with high Al content.

Flexible Gallium Nitride for High‐Performance, Strainable Radio‐Frequency Devices

“…The values of mobility and sheet carrier density on the flexible tape far exceed previous reports of GaN HEMTs grown on 2D materials, [25] and represent state of the art electron transport behavior even for rigid AlGaN/GaN structures grown on conventional substrates. [40,41] The 2DEG transport properties reflect the excellent material quality and necessary importance for epitaxial growth of GaN on a high-quality 2D BN layer. [32] Similar GaN devices for liftoff and transfer are grown on silicon and are typically of lower quality due to a lattice mismatch of more than 17%, substrate bowing, and thermal expansion mismatch.…”

“…The product of the mobility and sheet carrier density is directly related to the inverse of the sheet resistance, which slightly increases but remains within 1% of the starting value (as shown in Figure S6 in the Supporting Information). [40,41] The 2DEG transport properties reflect the excellent material quality and necessary importance for epitaxial growth of GaN on a high-quality 2D BN layer. [40,41] The 2DEG transport properties reflect the excellent material quality and necessary importance for epitaxial growth of GaN on a high-quality 2D BN layer.…”

Recent Advances in GaN‐Based Power HEMT Devices

“…Owing to the polarization effect and bandgap offset of AlGaN/GaN, the energy bands of heterojunction are bended downward to form a sharp quantum well, where the high‐intensity electrons are trapped at AlGaN/GaN interface. [ 25,26 ] The 2DEG channel is generated on the top of UID‐GaN layer that forms high‐density current from the Ohmic‐contact source to drain. [ 5 ] As a result, a Schottky gate is required to pinch off the normally‐on 2DEG channel.…”

A hybrid simulation technique for electrothermal studies of two-dimensional GaN-on-SiC high electron mobility transistors

“…35 For 2DEG, it is possible to compute the exact scattering rates as a function of wave vectors by Fermi's golden rule. 33,39,40 However, this may largely increase the computational load and is not suitable for the hybrid simulation technique. In the simplified treatment, the 3D electronphonon scattering formulation has been generally adopted in the literature 14,19,24,34,35 and is justified by good fittings with experiments.…”