Facet-controlled three-step growth of high-quality GaN on sapphire substrates by mass-production-type metalorganic vapor phase epitaxy

Three-step growth using facet-controlled GaN (FC-GaN) technique was demonstrated to successfully grow high-quality GaN on sapphire substrates by mass-production-type metalorganic vapor phase epitaxy. The FC-GaN consists of an island-like structure with intentionally formed inclined { 1 0 1 ¯ 1 } facets. Growth time, temperature, pressure and carrier gas were employed as parameters to control island and facet formation of the FC-GaN. The dependence of full width at half maximum (FWHM) of X-ray rocking curve (XRC) on growth time and temperature of FC-GaN was investigated. FWHM of XRC has a minimum peak versus growth temperature of FC-GaN. Cross-sectional transparent electron microscopy analysis revealed that dislocations were bent where the { 1 0 1 ¯ 1 } facets formed, and the threading dislocation (TD) density at GaN surface was reduced. Correlation between FC-GaN morphology and TD reduction efficiency was discussed.