Advanced III-nitride nanorod pixel structures for AR near-eye display applications

Augmented-reality (AR) near-eye displays impose simultaneous requirements of extreme luminance, ultra-high pixel density, high color purity, and power efficiency under tight thermal and form-factor constraints. Conventional planar micro-LEDs face an escalating efficiency penalty as the pixel dimension approaches the sub-10-µm regime, while their broad Lambertian emission and limited spectral purity complicate waveguide-coupled optics and outdoor readability. This invited paper reviews recent progress toward III-nitride nanorod and nanowire pixel platforms that combine geometry-enabled color tuning, nonpolar core-shell heterostructures, and photonic engineering to boost light extraction and emission directionality. We summarize (i) monolithic full-color nanowire pixels enabled by diameter-controlled InGaN emission, (ii) DBR-free surface-emitting photonic-crystal lasers and tunnel-junction integration for ultracompact, electrically injected pixels, (iii) in-situ reflector approaches for improved outcoupling, and (iv) recently identified photonic-recycling ("quantum geyser") dynamics in InGaN nanorod arrays and directionally emitting single-nanowire continuous-wave lasing pixels. Remaining challenges and outlook for manufacturable AR display engines are discussed.