Full color LEDs cut down to size

KAUST scientists have created micrometer-scale light-emitting diodes of unprecedented small size that could be used in mobile phone screens or televisions.

© 2021 KAUST.

Micrometer-scale light-emitting diodes (μLEDs) are the ideal building block for next-generation microLED displays used in head-mounted monitors, mobile phones and televisions because they are bright, respond quickly, offer longevity and consume little energy. KAUST researchers have shown that these scaled-down devices can efficiently emit light across the entire visible-light spectrum.

Just as with conventional LED displays, full-color μLEDs products will require arrays of blue, green and red light sources. Nitride-based alloys are a group of semiconducting materials that offer one route to achieving this because, with the right chemical mix, they can emit all three colors.

However, when nitride devices are reduced in size to micrometer scales, they become very poor emitters of light. “The main obstacle to reducing the size of the devices is the damage to the sidewalls of the LED structure generated during the fabrication process,” explains Ph.D. student Martin Velazquez-Rizo. “Defects provide an electrical path for a leakage current that does not contribute to the light emission.” This effect gets worse as the size of the LED shrinks, which has limited the LED size to approximately 400 by 400 micrometers.

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