Epitaxial growth and structural analysis of AlN/GaN heterostructures

Single crystal AlN thin films were epitaxially grown on GaN/sapphire (0001) substrates on a macroscopic scale by magnetron sputtering. The microscopic structure and orientation degree of the AlN epilayers were studied by high-resolution transmission electron microscopy, high-resolution x-ray diffraction, and reciprocal spacing mapping. It was revealed that the AlN epilayers have high in-plane and out-of-plane orientation degrees and low defect density. The electrical and optical properties of the AlN epilayers were also studied, and the results suggest that the AlN epilayers grown by sputtering may be employed in the fabrication of GaN-based light-emitting diode devices with increased efficiency.