Epitaxial growth of a high-quality GaN/AlN heterostructure for the development of an AlN-back barrier high-electron-mobility-transistor

Cross-sectional bright field TEM images of the GaN/AlN heterojunction with a 2D-GaN only channel layer (a, b) and 3D/2D GaN channel layer (c, d). For the proposed 3D/2D structure, dislocations are primarily located in the 3D-GaN layer.