The Michigan Engineer News Center

Full-color nano-LEDs for better, longer lasting LED performance

Research led by Prof. Zetian Mi to advance LEDs for high-efficiency, high-performance displays is recognized with the Distinguished Paper Award from the Society for Information Display.| Short Read
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Prof. Zetian Mi and his team earned the Society for Information Display’s Distinguished Paper Award for their research on developing multicolor, single nanowire LEDs. These LEDs can improve high-resolution imaging and displays, lighting, communications, sensing, and medical diagnostics. Specifically, they can support high-resolution display technologies like VR headsets and Google Glass. They could also be capable of delivering invisible ultraviolet-spectrum light that has been proven effective in water and air purification and sterilization of medical equipment.

“At first, we focused on individual nanowires where we could control the image and color by just changing the diameter of the nanowires,” says ECE postdoctoral researcher Xianhe Liu, who was lead author on the paper. “By assembling the nanowires into an array, we were able to achieve multicolored emission, which can support three-dimensional projection displays, flexible displays, and even virtual retinal display technologies.”

These nano-LEDs and their resulting structures are integrated on a single chip and grown in a single process step using selective growth. This boosts efficiency and performance while lowering costs—bridging a gap that has historically limited LED use in numerous markets. The previous GaN-based LEDs were bright, stable, and efficient, but were not capable of multicolor emissions. However, InGaN nanowire structure makes it possible to achieve multicolor emission on one substrate

“InGaN nanowire structure allows us to meet the next generation requirements,” Liu says.

The U-M startup NS Nanotech, co-founded by Mi, is working on bringing this technology to market. The micro-LEDs were fabricated using the Lurie Nanofabrication Facility (LNF). The paper is “Submicron full-color LED pixels for microdisplays and micro-LED main displays.”

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Hayley Hanway

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Researchers
  • Zetian Mi

    Zetian Mi

    Professor, Electrical Engineering and Computer Science

The electrons absorb laser light and set up “momentum combs” (the hills) spanning the energy valleys within the material (the red line). When the electrons have an energy allowed by the quantum mechanical structure of the material—and also touch the edge of the valley—they emit light. This is why some teeth of the combs are bright and some are dark. By measuring the emitted light and precisely locating its source, the research mapped out the energy valleys in a 2D crystal of tungsten diselenide. Credit: Markus Borsch, Quantum Science Theory Lab, University of Michigan.

Mapping quantum structures with light to unlock their capabilities

Rather than installing new “2D” semiconductors in devices to see what they can do, this new method puts them through their paces with lasers and light detectors. | Medium Read