Epilayers of GaN which were about 1μm thick were grown directly onto 6H-type (00•1) substrates by means of direct-current plasma-assisted molecular beam epitaxy. High-resolution X-ray diffraction and 2-dimensional triple-axis mapping were used to characterize the epilayers. A full-width at half-maximum of 11.9arcmin for an ω-scan, and of 1.2arcmin for an ω/2θ-scan, were observed. Study of the rocking curves showed that there were large mosaics in the GaN epilayers. Two-dimensional triple-axis mapping showed that the GaN mosaics were misoriented in the (00•1) plane but were relatively uniform in the direction perpendicular to the plane. A mosaic model was proposed in order to explain the phenomenon, and the dislocation density was estimated to be equal to about 2 x 109/cm2; according to this model.

Growth and Mosaic Model of GaN Grown Directly onto 6H-SiC(0001) by Direct-Current Plasma-Assisted Molecular Beam Epitaxy. Q.K.Yang, A.Z.Li, Y.G.Zhang, B.Yang, O.Brandt, K.Ploog: Journal of Crystal Growth, 1998, 192[1-2], 28-32