Ultra-Tiny Red LEDs Pair with Blue and Green Variants to Push Towards a Future of High-Res Displays

Researchers at the King Abdullah University of Science and Technology (KAUST) in Saudi Arabia say they have come up with a means of dramatically reducing the size of red-color nitride-alloy LEDs to just 17x17 micrometers — paving the way for ultra-high resolution LED displays in the future.

LEDs based on nitride alloys are commonly used for display projects, thanks to a key feature: By varying the chemical mix, they can produce red, green, and blue light — the three colors required for an RGB display.

Shrinking the LEDs down, however, is a challenge, limiting the maximum resolution of a nitride LED display. “The main obstacle to reducing the size of the [LED] devices is the damage to the sidewalls of the LED structure generated during the fabrication process," says KAUST PhD student Martin Velazquez-Rizo of his team's research. "Defects provide an electrical path for a leakage current that does not contribute to the light emission."

Previously, nitride LEDs were limited to a size of 400x400 micrometers - around the same size on a side as the width of six human hairs. The red prototypes developed by Velazquez-Rizo and colleagues, though, measure just 17x17 micrometers — nearly 24 times smaller than the previous limit — while offering full brightness, something previously achieved only with green and blue versions.

The secret: A carefully-calibrated atom deposition technique coupled with a post-manufacture chemical treatment capable of repairing the damage to the LEDs' sidewalls. The resulting red LEDs were then paired with green and blue nitride LEDs to create a device with a full color range — the precursor to ultra-high-resolution LED displays.

“The next step in our research is to further improve the efficiency of our μLEDs," says Velazquez-Rizo, "and decrease their lateral dimensions below 10 micrometers."

The team's work has been published under open-access terms in the journal Photonics Research.