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

We have investigated the microstructures of GaN films laterally epitaxially overgrown (LEO) on Si (111) substrates by hydride vapor 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 (66°and 90°) 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 5μm perpendicular to the mask stripes. The indistinction selective growth in the top surface is discussed.