High-quality GaN on AIN multiple intermediate layer with migration enhanced epitaxy by RF-molecular beam epitaxy

High-speed GaN growth of 1.0 μm/h with migration enhanced epitaxy (MEE) by molecular beam epitaxy using rf-plasma nitrogen (RF-MBE) was demonstrated. The electron mobility of MEE-GaN was 362 cm2/V·s for the electron density of 1.7 × 1017 cm-3 at room temperature. The threading dislocation density of MEE-GaN was estimated to be 1.0-3.0 × 1010 cm-2 based on the cross-sectional transmission electron microscope (TEM) image. The remarkable improvement of electrical properties was obtained by the introduction of a high-temperature (750°C) grown AIN/GaN multiple intermediate layer (AIN-MIL). The cross-sectional TEM image showed that threading dislocations were bent or terminated at the AIN-MIL. The highest room temperature mobility of 668 cm2V·s was obtained at the electron density of 9.5 × 1016 cm-3. The low-temperature peak mobility was 2340 cm2/V·s at 90 K.