Structural investigation of GaN layers grown on Si(111) substrates using anitridated AlAs buffer layer

GaN layers are grown by metalorganic chemical vapor deposition (MOCVD) on S i(1 1 1) substrates. X-ray diffraction (XRD) measurements and cross-section transmission electron microscopy (TEM) show a comparable crystalline quali ty of the samples to the quality of GaN/sapphire samples. Both the characte ristic symmetric GaN(0 0 0 2) and the asymmetric GaN(10 - 15) X-ray reflect ions have full-widths at half-maximum of 600-700 arcsec. The dislocation de nsity as estimated from TEM investigation is found to be of the order of 10 (10) cm (-2). The initially deposited AlAs nucleation layer is transformed into AIN by supplying ammonia to the AlAs layer. This buffer layer can be c ompletely etched off thus providing an easy way for substrate-layer separat ion after growth, an essential step for avoiding absorption of radiation em itted from nitride layers in the silicon substrate. (C) 2000 Elsevier Scien ce B.V. All rights reserved.