Surface-Plasmon-Coupled Blue InGaN/GaN Micro-LEDs with Oxide–Metal–Oxide Capping Layer Compatible to Chip Fabrication Process

Blue InGaN/GaN micro-light-emitting diodes are promising for next-generation displays, but their efficiency severely diminishes at dimensions below ∼5 µm due to dominant sidewall-induced non-radiative recombination. To overcome this fundamental limitation, we propose a multifunctional oxide-metal-oxide (OMO) strategy to simultaneously passivate sidewall defects and introduce a highly efficient radiative recombination pathway via localized surface plasmon (LSP)-exciton coupling. This OMO configuration integrates conformal Al₂O₃ layers for effective surface passivation with thermally dewetted Ag nanoparticles, which serve as plasmonic centers. By precisely aligning the LSP resonance to the blue emission wavelength (∼450 nm), the OMO-integrated 4 × 4 µm² devices exhibit a 61% enhancement in micro-photoluminescence and a further 27% increase in external quantum efficiency compared with atomic-layer-deposited Al₂O₃ references. These results suggest that the plasmonic OMO sidewall architecture is a wafer-scale process-compatible and potentially scalable route toward high-performance, ultra-small micro-LED display pixels for future display applications.