X-ray diffraction study of gallium nitride grown by MOCVD

An X-ray diffraction study of gallium nitride grown on the c-plane (0001) and r-plane (0112) of sapphire substrates by metal organic chemical vapour deposition using triethylgallium and ammonia was performed. By measuring asymmetric reflections with a ω-2θ two-circle diffractometer, lattice constants of α-GaN could be resolved for both substrate orientations and the epitaxial relationships could be confirmed. Additionally, the existence of β-GaN on the r-plane sapphire substrate could be deterimined. Pole figure measurements show different qualities of in-plane orientation of the α-GaN layers for the two substrate orientations.