Shown above is a schematic diagram of the technology for ultra-high-density sub-micron-sized pixels through the focused ion beam irradiation on an LED device. KAIST said that its research team had developed a technology of enabling ultra-high-resolution LED. Photo courtesy of KAIST

Researchers develop tech with sub-micrometer scale pixels

A team of researchers at the Korea Advanced Institute of Science and Technology (KAIST) announced on Feb. 22 that they had developed a technology for ultra-high-resolution LED.

The team headed by Prof. Cho Yong-hoon noted that their new findings had been based on sub-micrometer scale pixels _ 0.5 micron-scale pixels smaller than a hundredth of a human hair.

Ultra-high-resolution displays are regarded as essential elements for developing futuristic electronic products, including smartwatches and AR/VR devices.

Typically, pixelation of ultra-high-resolution LED displays usually relies on the etching method that physically cuts the area around the pixel.

As the pixel becomes smaller due to the occurrence of various defects around it, however, such an approach leads to side effects like leakage of current increased and decreased light-emission efficiency.

In addition, various complex processes such as patterning for pixelation and post-processing for prevention of leakage current are required, according to KAIST.

Prof. Cho’s team dealt with the hitches through a technology that could create pixels down to the size of a microscale without the complicated pre- and post-processing using a focused ion beam.

The method had the advantage of being able to freely set the shape of the emitting pixel without causing any structural deformation on the material surface by controlling the intensity of the focused ion beam.

The research team used a focused ion beam whose intensity was softened to the extent that the surface was not shaved and found that not only the light-emission rapidly decreased in the area hit by the focused ion beam, but also the local resistance greatly increased. 

As a result, while the surface of the LED is kept flat, the portion hit by the focused ion beam is optically and electrically isolated, enabling pixelation for independent operation.

“We have newly developed a technology that can create sub-micron-scale pixels without complicated processes using a focused ion beam, which will be a base technology that can be applied to next-generation ultra-high-resolution displays and nano-photoelectronic devices,” Prof. Cho said.