Microstructures of GaN Films Laterally Overgrown on Si(111) by Hydride Vapour Phase Epitaxy

We have investigated the microstructures of GaN films laterally epitaxially overgrown (LEO) on Si(111) substrates using hydride vapour phase epitaxy. The threading dislocation density in the LEO GaN is reduced by about two orders. Different etching angles of the two sidewalls of SiO2 masks (66o and 90o) lead to the asymmetry of the LEO and cause the particular microstructures of LEO GaN. In micro-Raman spectra, the intensities vary weakly periodically about 5 µm perpendicular to the mask stripes. The indistinct selective growth in the top surface is discussed.