The In-Plane-Two-Folders Symmetric a-Plane AlN Epitaxy on r-Plane Sapphire Substrate

In the present work, a single-crystalline epitaxial nonpolar a-plane AlN film with in-plane two-folder symmetries was successfully achieved on an r-plane sapphire substrate, by combining physical vapor deposition and high-temperature annealing technique. Moreover, varying thickness, evolution of crystalline quality structure were systematically investigated using X-ray diffraction, Raman spectroscopy, atomic force microscopy. The much improved treatment. Most importantly, when thickness increased up to 1000 nm, lattice found endure strong distortion along out-of-plane direction, showed obvious expansion. change surface morphology induced also tracked, displayed structural anisotropy [11¯00] direction. Our results act as crucial platform better understand employ template; in particular, it is importance for subsequent device fabrication.