Fig. 4: EQE, far-field emission distribution and electric field profile of the red-emitting micro-LEDs.

a Measured relative EQE of devices with different surface passivation conditions. b Far-field angular distribution of EL intensity. c Calculated far-field radiation pattern of a PhC structure with a of 320 nm, d of 240 nm and Al₂O₃ passivation of 10 nm. d Schematic showing propagating directions of coupled waves along the Γ-M directions. e Calculated electric field distribution within the PhC structure. The white arrows are the Poynting vectors in the GaN substrate. f Benchmark of EQE value and linewidth value for some previously InGaN-based red micro-LEDs with device areas ≤ 400 µm^{2 12,15,16,17,24,48,49,50,51,52,53,54,55}