Ultra-dense Green InGaN/GaN Nanoscale Pixels with High Luminescence Stability and Uniformity for Near-Eye Displays

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Near-eye display technologies require ultra-dense, stable, full-color nanoscale pixels.
• Existing green Indium Gallium Nitride (InGaN)-based micro-LEDs suffer from low efficiency and poor wavelength stability due to surface defects and quantum-confined Stark effect.
• These limitations hinder the development of virtual and augmented-reality glasses.

Purpose of the Study:

• To report the nanoscale pixelation of green Indium Gallium Nitride/Gallium Nitride (InGaN/GaN) LEDs using strain-engineered ultra-dense nanowire (NW) arrays.
• To address the bottlenecks of low efficiency and inadequate wavelength stability in green micro-LEDs for advanced display applications.

Main Methods:

• Fabrication of ultra-dense NW arrays (∼36,000 pixels per inch) using a top-down approach.
• Incorporation of strain-engineered axial multi-quantum wells within the NWs.
• Utilized finite difference time domain (FDTD) simulations to analyze emission enhancement.

Main Results:

• Achieved stable peak wavelength emission at ∼500 nm across a wide range of current densities (∼4 A/cm² to ∼1 kA/cm²).
• Demonstrated significantly enhanced wavelength stability with a reduced blue-shift (∼4 nm) due to suppressed electric fields from strain relaxation.
• Observed increased emission due to enhanced spontaneous emission rates (Purcell factor ≈2) in ultra-dense NWs.

Conclusions:

• The developed strain-engineered NW arrays provide a viable route for nanoscale pixels with high luminescence stability and wafer-scale uniformity.
• This approach overcomes critical limitations in green InGaN/GaN LEDs, enabling high-performance next-generation near-eye displays.
• Top-down fabricated NWs exhibit superior uniformity and light output compared to bottom-up grown heterostructures.