Physics / mechanism
Micro-LEDs are inorganic III-nitride (typically GaN-on-Si or GaN-on-sapphire) or AlInGaP emitters with pixel pitch below ~100 µm, often 1–50 µm for high-density displays. Electroluminescence efficiency peaks at optimal current density; at micro-scale, external quantum efficiency (EQE) degrades due to surface recombination at mesa sidewalls — the “size-effect” problem. State-of-the-art EQE sits ~10–20% at small pitches without passivation; best-in-class (Porotech, Apple internal) pushes toward 40%+ with ALD sidewall passivation. Key fabrication bottleneck: mass transfer of millions of dies at yield >99.9999%. Peak brightness >1M nits; contrast ratio effectively infinite (per-pixel off-state).
Competitive landscape
OLED is the primary incumbent — flexible, mature supply chain, good EQE, but limited peak brightness, burn-in susceptibility, and lifetime under high-luminance operation. LCD+mini-LED backlight is a near-term bridge. Quantum-dot color conversion (QDCC) layered on blue micro-LED is a leading color-patterning route vs. direct RGB epitaxy. Key competing approaches:
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.