Organized AlN Nanowire Arrays by Hybrid Approach of Top-Down Processing and MOVPE Overgrowth for Deep UV Emission Devices

The fabrication of organized AlN nanowires with well faceted m -sidewalls is demonstrated, exhibiting a narrow near-band-edge emission that confirms the high quality of the AlN materials. In the first step, a top-down approach combining a plasma etching process and a subsequent wet KOH etching process allows for the fabrication of strain-free AlN nanopillars with various densities and diameters as small as 250 nm with m -oriented facets. In a second step, optimized overgrowth by MOVPE is performed to recover m -oriented hexagonal facets. A growth model is proposed to fit the evolution of the AlN lateral growth rate as a function of the spacing and diameter of the AlN nanopillars, highlighting two main contributions: diffusion from the substrate and direct growth from the vapor phase. Cathodoluminescence measurements at 5 and 300 K reveal that the overgrown AlN layer exhibits an intense AlN near-band-edge emission, confirming that this hybrid approach is suitable to create high-quality m -oriented AlN templates.