GaN catalyzed nucleation of thin low threading dislocation GaN on sapphire

Because of the presence of a GaN surface during GaN nucleation and growth on sapphire substrates, a substantial improvement in crystal quality, as observed by narrowing of the x-ray diffraction rocking curve peaks corresponding to symmetric (0002) and asymmetric (10–12) reflections, was observed. Using this method, a GaN buffer layer with a thickness of about 1 μm and a crystal quality comparable to that of the more commonly used thicker, about 3 μm, GaN buffer layer on sapphire was obtained. In addition, deposition of GaN layers as thin as 0.6 μm on sapphire yielded a device-grade epitaxial surface exhibiting low roughness, as confirmed by atomic force microscopy.