Newest faculty member, Hyunseok Kim, hits the ground running with Samsung grant

Hyunseok Kim is one of the newest faculty members of the Holonyak Micro & Nanotechnology Laboratory (HMNTL) and the department of electrical & computer engineering (ECE) at the University of Illinois Urbana-Champaign. His research centers on building functional electronic and optoelectronic platforms.

Kim grew up in South Korea and earned his B.S. in electrical engineering from Seoul National University. He then moved to the United States where he got his Ph.D. in electrical & computer engineering from the University of California, Los Angeles and did a postdoc in mechanical engineering at Massachusetts Institute of Technology. Following his postdoc, Kim worked as a research scientist at MIT before joining the Illinois faculty in spring 2024.

“I am really excited to be part of both ECE and HMNTL,” Kim says. “I cannot emphasize enough how supportive the environment is here and how helpful everyone has been. I have the resources I need so that I can really explore the stuff I have always dreamed of. There are so many world-class researchers here which provides me a lot of opportunities for collaboration because our research is very interdisciplinary.”

Kim’s research at Illinois intersects physics, electrical engineering and materials science. “I’m primarily interested in developing new material building blocks for electronics applications since we have been relying on silicon for more than a few decades,” he says. In recent years, researchers have been on the hunt for a new semiconductor material to replace or even boost the performance of silicon-based electronics and other optoelectronics (light-emitting/detecting devices). Kim is focused on two-dimensional (2D) materials, which are atomically thin, as a replacement for silicon.

“By merging those 2D materials with conventional materials, as well as synthesizing new materials, we will be able to harness new physical phenomena,” Kim says. “With those new material building blocks, I am interested in developing new types of devices, new types of transistors, and also optoelectronics like LEDs, lasers and photodetectors.”

In his young career so far, Kim already has a long publication record in numerous high impact journals, including Nature, Science, Nature Nanotechnology and Nature Electronics. He has also recently received a grant from the Samsung Global Research Outreach program for $150,000 for one year, which can be renewed for a total of three years. The program calls for innovate research proposals from leading universities worldwide to foster technological innovation aligned with Samsung’s various research fields. This project, “Full-color micro-LEDs via advanced epitaxy and integration techniques,” will be co-led by HMTNL Director Minjoo Larry Lee.

The goal of this project is to develop vertically stacked full-color micro-LEDs. Upon completion of the proposed research, Kim and his team plan to demonstrate micro-LED chips composed of vertically stacked red, green and blue (RGB) pixels integrated into display panels.

Current display technology is generally one of two kinds: organic LED (OLED) or liquid crystal display (LCD). OLEDs use organic materials to emit light, but a major pitfall is that these materials degrade easily which limits the overall lifespan. LCDs use backlights to make images visible (as opposed to the individual pixels of OLEDs). They tend to have better lifespans than OLEDs, but LCDs are limited by contrast. Even on a dark screen, some dim background light can still be seen.

Micro-LED is a new, emerging type of display that consists of an array of microscopic LEDs. Unlike OLEDs, micro-LEDs use inorganic materials to generate light resulting in an extremely long lifetime and high efficiency. With the advantages of both OLEDs and LCDs, micro-LEDs are poised to be the next generation of display technology.

But they are not without their own limitations. Production of micro-LED displays is incredibly challenging as 10s of millions of pixels need to be reliably transferred to the display panel. When it comes to displays, consumers don’t tolerate defects or missing pixels, therefore 100% yield, or close to 100% yield, is necessary. This difficulty in assembly makes the current price impractical for the average buyer.

Kim’s research focuses on two key concepts to help advance micro-LED technology. The first is vertically stacking RBG sub-pixels to make each overall pixel more compact. In current displays, the three sub-pixels are in plane (side-by-side). Vertically stacking the sub-pixels means the overall pixel will occupy a three times smaller footprint. Another advantage of this approach is that each pixel can be assembled vertically and then moved together as one unit onto the display panel.

The second key concept Kim proposes is a new method for transferring pixels onto the display panel. Rather than picking up each pixel and placing it onto a panel, a process aptly called “pick-and-place,” a self-assembly technique would use liquid to transfer the pixels. Millions of pixels can be mixed with a solvent and poured onto a panel and the pixels would automatically fill in the pockets of the display panel. The liquid solvent would then be flushed out, leaving a display panel with perfectly assembled pixels.

Kim acknowledges that this project is quite ambitious but the scientific and commercial impacts of the project are worth the challenge. He says, “I think this is a good example of using science to make something innovative that can be beneficial both commercially and for our everyday lives.”