Design rules for core/shell nanowire resonant emitters

We study design principles to boost the extraction of light from core/shell GaN nanowire optical emitters. A full-vectorial electromagnetic simulation reveals that the extraction efficiency of an emitter within a nanowire cavity depends strongly on its position; the efficiency becomes maximized as the emitter’s location approaches the center of the structure. The total extraction of light is sinusoidally modulated by the nanowire diameter, which is directly correlated with optical resonances. The introduction of a conformal dielectric coating on a nanowire leads to a dramatic enhancement in the extraction efficiency, which results from an increase in side emission owing to an optical antenna effect. A simple high-refractive-index dielectric coating approximately doubles the total extraction efficiency of a nanowire LED. These numerical findings will be valuable in providing strategies for high-efficiency nanowire-based optical emitters.