Light emitting diodes (LEDs) have been powering displays for years, but new developments in fabricating red LEDs, based on blue-emitting semiconductor indium gallium nitride, may lead to a new range of displays in the future.
LEDs are optical devices that can emit across the spectrum from ultraviolet to blue, green, red and into the infrared spectrum. Tiny RGB devices, called micro-LEDs, can be used to make vivid-color displays possible in the next generation of monitors and televisions.
Researchers from King Abdullah University of Science & Technology (KAUST) made the discovery using red-light LEDs made from indium gallium phosphide (InGaP), while blue and green LEDs are comprised of indium gallium nitride (InGaN) semiconductors. Because RGB displays require the mass transfer of separate blue, green and red LEDs together, an easier solution could be to create different colored LEDs all on a single semiconductor chip.
The only solution to making this is monolithic RGB micro-LEDs to use InGaN that can shift its emission from blue to green, yellow and red by introducing more indium into the mix. Additionally, it has been suggested that InGaN red LEDs perform better than current InGaP ones.
"A critical disadvantage of InGaP red LEDs is that they are not stable when operated at high temperatures," said Zhe Zhuang, a researcher at KAUST. "Therefore, we created InGaN red LEDs of different designs to realize very stable red-light InGaN sources at high temperatures."
KAUST developed an InGaN red LED structure with output power that is more stable than that of InGaP red LEDs. Additionally, the emission color shift at high temperatures was less than half of that of those made with InGaP.
The team also developed transparent electrical contacts using a thin film of indium-tin-oxide (ITO), which allows for a current to pass through their InGaN-based amber and red LEDs.
