Fabrication of submicron active-region-buried GaN hexagonal frustum structures by selective area growth for directional micro-LEDs

•Proposed a submicron hexagonal GaN frustum for application in directional micro-LEDs.•Emission patterns from embedded active regions were simulated using the FDTD method.•Target frustum geometry was established based on the simulation results.•These frustums were grown using a two-step growth sequence. We proposed an active-region-buried submicron hexagonal GaN frustum for application in directional micro-LEDs and simulated the emission patterns from the embedded active region in the hexagonal frustum using the finite-difference time-domain (FDTD) method. Based on the simulated results, the target geometry of the frustum structure was designed for actual fabrication. The submicron active-region-buried GaN hexagonal frustums were fabricated by selective area growth using a two-step growth method. The two-step growth sequence was used to form a wider top-face of the frustum than that on an embedded InGaN layer. The TMG flow rate and reactor pressures were experimentally varied and the morphology of the grown frustums was characterized by SEM. As a result, a hexagonal frustum similar to the target geometry was obtained.