Spatially resolved cathodoluminescence study of selected-area ELO-GaN grown on Si(111) substrates

摘要

Crack-free thick ( > 10 μm) GaN layers that were grown on Si(111) substrates using selected-area epitaxial lateral overgrowth (ELO) method were investigated by spatially resolved cathodoluminescence microscopy at 15 K. ELO-mask materials employed in this study are SiO_2 deposited by sputtering and SiN_x formed by nitriding Si-surface areas (grooves) between GaN seeds. Local CL spectra near the GaN surface exhibited sharp excitonic luminescence with FWHM of 4.3 meV for the layers grown on a SiO_2-masked Si substrate. The intensity of the sharp excitonic luminescence continued to increase, without any observable saturation, as the sampling position approaches to the surface. It is experimentally proven that thick high-quality GaN without cracks can be grown on Si(111).