Significant red-emission enhancement using column-top-exposed InGaN-based nanocolumn plasmonic crystals with honeycomb lattice

Red emission remains a major bottleneck for practical full-color micro-light-emitting diodes (microLEDs) because the quantum efficiencies of InGaN decrease in the long-wavelength region. To enhance red emission, this study developed a honeycomb-latticed InGaN/GaN nanocolumn array integrated with an Ag-based plasmonic LED structure. Finite-difference time-domain simulations were used to optimize the lattice parameters, identifying a = 220 nm and D = 190 nm as the optimal geometries. This design provided an electric-field enhancement of approximately 4.5 at λ = 623 nm, indicating strong surface plasmon polariton coupling in the red region. A device fabricated with the same parameters exhibited up to a 6.3-fold photoluminescence enhancement under surface excitation, outperforming the 5.9-fold enhancement previously achieved under backside excitation. These results demonstrate that honeycomb-latticed plasmonic engineering is effective for boosting red emission in InGaN-based structures and offers a promising route to high-efficiency red microLEDs.