Vertical full-colour micro-LEDs via 2D materials-based layer transfer

Area of Science:

• Optoelectronics
• Materials Science
• Nanotechnology

Background:

• Micro-LEDs (µLEDs) are crucial for augmented and virtual reality (AR/VR) displays due to high pixel density and luminance requirements.
• Conventional lateral assembly of red, green, and blue (RGB) µLEDs faces limitations in achieving desired pixel densities.
• Existing vertical µLED display approaches struggle with minimizing lateral dimensions of stacked components.

Purpose of the Study:

• To overcome limitations in µLED display manufacturing for AR/VR applications.
• To achieve unprecedented pixel density and reduced device size in full-color µLED displays.
• To demonstrate a novel fabrication method for vertically stacked µLEDs.

Main Methods:

• Utilized a two-dimensional (2D) materials-based layer transfer technique for LED growth.
• Employed remote or van der Waals epitaxy for near-submicron thick RGB LEDs on 2D material-coated substrates.
• Integrated mechanical release, stacking, and top-down fabrication for vertical assembly.
• Demonstrated vertical integration of blue µLEDs with silicon membrane transistors.

Main Results:

• Achieved the highest reported array density of 5,100 pixels per inch.
• Fabricated vertically stacked µLEDs with the smallest reported size of 4 µm.
• Obtained the smallest stack height of approximately 9 µm, enabling record density.
• Successfully demonstrated active matrix operation through integration with silicon transistors.

Conclusions:

• The developed 2D materials-based layer transfer technique enables ultra-high-density, full-color vertically stacked µLED displays.
• The achieved record density and small device size are critical advancements for next-generation AR/VR displays.
• This work presents a versatile platform for 3D integrated devices beyond display applications.