High-mobility AlGaN/GaN heterostructures grown by molecular-beam epitaxy on GaN templates prepared by hydride vapor phase epitaxy

Abstract

We report on the growth and transport properties of high-mobility two-dimensional electron gases (2DEGs) confined at the AlGaN/GaN interface grown by plasma-assisted molecular-beam epitaxy on GaN templates prepared by hydride vapor phase epitaxy. We have grown samples over a broad range of electron densities ranging from $n_s{\text{=6.9×10}}^{11}$ to ${\text{1.1×10}}^{13}\hspace{0.5em}{\mathrm{cm}}^{\mathrm{-2}},$ and at T=4.2 K, observe a peak mobility of 53 300 ${\mathrm{cm}}^{\mathrm{2}}\mathrm{/V s}$ at a density of ${\text{2.8×10}}^{12}\hspace{0.5em}{\mathrm{cm}}^{\mathrm{-2}}.$ Magnetotransport studies on these samples display exceptionally clean signatures of the quantum Hall effect. Our investigation of the dependence of 2DEG mobility on carrier concentration suggests that the low-temperature mobility in our AlGaN/GaN heterostructures is currently limited by the interplay between charged dislocation scattering and interface roughness.