Metal organic vapor phase epitaxy of high-indium-composition InGaN quantum dots towards red micro-LEDs

Micro-scale light-emitting diodes (micro-LEDs) are regarded as the next generation display technology. Compared to blue and green ones, InGaN-based red micro-LEDs require higher indium composition in their active region, which is quite challenging for material growth. Here, high-indium-composition InGaN quantum dots (QDs) with a density of 3 × 10 ¹⁰ cm ^-2 are self-assembly grown by metal-organic vapor phase epitaxy (MOVPE) based on a precursor-alternate-admittance method. The growth mechanism is systematically studied, and consequently a 613-nm red QDs sample with an internal quantum efficiency (IQE) of 12% is demonstrated. Furthermore, when micro-LEDs based on these red InGaN QDs with a chip size of 1-20 µm are fabricated, an electroluminescence blueshift to yellow and green is observed. The 20-µm and 1-µm micro-LEDs show 4.92% and 1.78% external quantum efficiency (EQE) at 0.3 and 20 A/cm ² , respectively. By introducing multiple quantum wells (MQWs) pre-strained layer beneath the QD layers, a 10-µm micro-LED with 638 nm emission wavelength is demonstrated, with a price of reduced EQE to 0.03% at 10 A/cm ² .