Ultrathin-barrier AlN/GaN heterostructures grown by rf plasma-assisted molecular beam epitaxy on freestanding GaN substrates
We report the structural and electrical properties of ultrathin-barrier AlN/GaN heterostructures grown on freestanding GaN substrates by rf plasma-assisted molecular beam epitaxy. Structures with barrier thicknesses between 1.5 nm and 7.5 nm were grown and characterized. We observe that AlN/GaN structures with barriers of 3.0 nm exhibit the highest Hall mobility, approximately 1700 cm2/Vs. Furthermore, the Hall mobility is much diminished in heterostructures with AlN barriers thicker than 4.5 nm, coincident with the onset of strain relaxation. Highlights •
Rf-MBE growth of AlN/GaN high electron mobility transistors.
AlN/GaN HEMTs on free standing GaN substrates.
Effect of barrier thickness on structural and electronic properties.