High-Quality AlN by Initial Layer-by-Layer Growth on Surface-Controlled 4H-SiC(0001) Substrate

The initial layer-by-layer growth of AlN was realized on a surface-controlled 4H–SiC(0001) substrate using plasma-assisted molecular-beam epitaxy (PA-MBE). To achieve initial two-dimensional (2D) growth, the control of SiC surface chemistry is very important as well as that of surface flatness. The effect of SiC preparation on the surface structure and chemical composition was investigated by using reflection high-energy electron diffraction (RHEED) and in situ X-ray photoelectron spectroscopy (XPS). The initial growth mode of AlN was strongly influenced by the removal of residual oxygen atoms from the SiC surface. Symmetrical and asymmetrical X-ray rocking curve (XRC) measurements revealed that initial 2D growth was essential to obtain the excellent crystalline quality of AlN layer.