Influence of SiH4 Flow Rate on GaN Films with In Situ SiNx Mask on Sapphire Surface

Abstract

Sapphire substrate was treated by SiH4under NH3atmosphere before GaN growth and nanosize islands SiNxmask was formed on the substrate. Properties of GaN films were investigated by high resolution X-ray diffraction, photoluminescence and transmission electron microscopy. The results indicated that the SiH4flow rate is an important factor affecting the size and density of SiNxmask besides SiH4treatment time.The GaN films grown on the SiNx-patterned sapphire substrate revealed an epitaxial lateral overgrowth mode, which affected 3D to 2D growth time and the microstructures of GaN films. The lowest FWHM value of (102) rocking curve was 286 arcsec. as the SiH4flow rate of 0.5sccm, with the calcultated edge-type dislocations density of 4.28×109cm-2.