Cantilever Epitaxy: A simple Lateral Growth Technique for Reducing DislocationDensitites in GaN and Other Nitrides

摘要

The high threading dislocation (TD) densities found in GaN that has been growndirectly on flat substrates degrade both the electronic and photonic properties of the material. The new technique of cantilever epitaxy (CE) can reduce the density of dislocations by 2 or more orders of magnitude. CE employs prepattemed substrates to provide reduced-dimension mesa regions and etched trenches that are spanned by lateral growth of GaN or AIGaN. The substrate is prepattemed with narrow lines and etched to a depth that permits coalescence of laterally growing III-N nucleated on the mesa surface before vertical growth fills the etched trench. Low dislocation densities typical of epitaxial lateral overgrowth (ELO) are obtained in the cantilever regions and the TD density is also reduced over the mesas up to 1 micrometer from the edge of the mesa support regions.