Design Principles and Performance Limitation of InGaN Nanowire Photonic Crystal Micro-LEDs

While micro-LEDs are crucial for ultrahigh resolution micro-displays, the efficiency of currently reported micro-LEDs degrades dramatically with decreasing size. Recently, the bottom-up nanowire approach has shown promise to break the efficiency bottleneck of this size effect. In this article, we investigated the design of nanowire photonic crystal structure for micro-LED applications and revealed its correlation with the Purcell effect. Key performance characteristics including efficiency, emission directionality, and spectral linewidth are thoroughly studied. For an LED structure with low internal quantum efficiency (IQE) of 10% due to high non-radiative recombination, an enhancement of ∼30% is found viable by using a properly designed photonic crystal. High emission directionality and a narrow spectral linewidth (∼ 5 nm) can be obtained with 60% of the light being emitted within a 20° acceptance angle.