Molecular beam epitaxial growth of GaN on 3C-SiC/Si(111) substrates using a thick AlN buffer layer

Hexagonal GaN films (∼3 μm) were grown on 3C-SiC/Si(111) and carbonized Si(111) substrates using a thick AlN buffer. Cracks are observed on the surface of the GaN film grown on the carbonized Si(111), while no cracks are visible on the 3C-SiC/Si(111). XRD exhibits polycrystalline nature of the GaN film grown on the carbonized Si(111) due to poorer crystalline quality of this substrate. Raman spectra reveal that all GaN layers are under tensile stress, and the GaN layer grown on 3C-SiC/Si(111) shows a very low stress value of σ_xx=0.65 GPa. In low-temperature photoluminescence spectra the remarkable donor-acceptor-pair recombination and yellow band can be attributed to the incorporation of Si impurities from the decomposition of SiC.