Monolithic GaN-Based Dual-Quantum-Well LEDs with Size-Controlled Color-Tunable White-Light Emission

Area of Science:

• Solid-state lighting
• Gallium Nitride (GaN)-based devices
• Semiconductor optoelectronics

Background:

• Traditional white light-emitting diodes (LEDs) often rely on phosphors, which can limit efficiency and color rendering.
• Achieving tunable white light emission from a single monolithic device presents a significant challenge in solid-state lighting.

Purpose of the Study:

• To develop a monolithic GaN-based LED platform for color-tunable white light emission.
• To demonstrate the feasibility of tuning white light color temperature and chromaticity through LED size scaling.

Main Methods:

• Fabrication of a monolithic GaN-based LED platform with a dual-composition multi-quantum well (MQW) structure.
• Utilizing LED size scaling (800 µm down to 50 µm) to control injection current density and carrier distribution.
• Employing high-resolution transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) for material analysis.

Main Results:

• Demonstrated color-tunable white light emission by varying LED size.
• Observed emission shifts from red-orange (580 nm, 2536 K) in larger LEDs to blue (450 nm, 9425 K) in smaller LEDs.
• Confirmed indium segregation and phase separation in the quantum wells via TEM/EDX, enabling broad spectrum emission.

Conclusions:

• Monolithic GaN-based LEDs with size-tunable white light emission are achievable.
• This phosphor-free approach offers precise control over color temperature and chromaticity for adaptive lighting.
• The technology presents a promising strategy for compact and efficient solid-state lighting applications.