Fabrication of GaN hexagonal pyramids on dot-patterned GaN/sapphire substrates via selective metalorganic vapor phase epitaxy

Three-dimensional facet structure of GaN has been fabricated on dot-patterned GaN (0001)/sapphire substrates using SiO 2 masks via selective epitaxial growth by metalorganic vapor phase epitaxy. The dot patterns are hexagons with width of 5 µ m and spacing of 10 µ m. The facet structure comprises a hexagonal pyramid covered with six {11̄01} facets. A stable and self-limited (0001) facet appears on the top, depending on growth conditions. The area of the (0001) facet increases with increasing growth temperature or with decreasing flow rate of trimethylgallium. The (0001) facet formation is determined by the diffusion length of a Ga atom on the (0001) surface.