Computer technology leaped from clunky vacuum tubes to sleek chips in the last century, and the coming years could bring another sea change of equal magnitude. That’s the goal of Columbia University researcher Young Duck Kim, and his new graphene “light bulb” could light the way.
Kim has developed a nanoscale light-emitting device that can be put on a chip. It could help usher in a new generation of ultra fast, small, lightweight photonic computers, which use light instead of an electric current.
When that does happen, Lego can take part of the credit. Working with the tiny blocks as a child made Kim aware that he enjoyed making things with his hands. It also got him accustomed to the idea that anything can happen when the same elements come together in different configurations.
“My dream was to become a scientist, especially a physicist,” Kim says. His academic career did begin with physics, but along the way he found that the allure of working with his hands was irresistible.
“As it turned out, theory does not fit me,” he chuckles. “I liked assembling Legos and creating something new. The process was fascinating.”
The realization of his true passion propelled Kim into the hyper-miniature world of nano electromechanical systems, where instead of snapping Lego blocks together, he learned how to construct new architecture at the atomic level.
Kim notes that another lifelong passion helped him make the transition to his newfound career. As an avid snowboarder and skateboarder, he knew that hard practice and many failures precede the mastery of difficult physical maneuvers. In the lab, that translated into patiently learning how to manipulate the delicate equipment required to work with graphene, a two-dimensional form of carbon just one atom thick.
“Nanoscale research is similar to extreme sports,” he explains. “You don’t give up, and you try, try until you succeed.”
Between Lego and extreme sports, Kim also developed a keen sense of persistence, an important trait when it came to cultivating a laboratory happenstance into a game-changing discovery.
The new graphene light bulb did actually come about by accident. Four years ago, Kim was trying to “clean” graphene by heating it with an electric current, when something odd happened. As he slowly increased the current, the graphene unexpectedly began to emit a bright, visible light.
Kim was observing a phenomenon that had been eluding graphene researchers ever since the material was first discovered in 2004. He likens the experience to the apocryphal “egg of Columbus” story, in which the path to a significant discovery seems simple and obvious — after the discovery is made, that is.
While Kim immediately sensed that he was on to something big, getting others on board twas a different matter. He had to make a convincing case for graphene in order to catch the attention of potential collaborators.
Assembling a research team was the critical breakthrough, as Kim recalls. “I knew I had to catalyze this thing, so I visit labs, I find people, I show them the data and the picture and the movie, we talk…without other people I cannot do it.”
Once again, patience and persistence paid off. Working through the Columbia Engineering lab of Professor James Hone, Kim recruited colleagues to help him quantify the light emitting from the graphene, and to understand the exact mechanism behind it.
The result was a paper published online in June by Nature Nanotechnology under the straightforward title “Bright Visible Light Emission from Graphene,” confirming and elaborating upon Kim’s original discovery. In addition to Kim and co-author Hone from Columbia Engineering, scientists from Seoul National University and the Korea Research Institute of Standards and Science contributed to the research.
The graphene light bulb almost literally shrinks the traditional Edison light bulb down to atomic size, and places it on the surface of a computer chip. As Kim notes, Thomas Edison also turned to carbon for his light bulb filament, as did other early pioneers in illumination.
Other materials fall apart when heated, or radiate far too much heat to be used on a chip. The new study shows that graphene suspended between two electrodes can be heated to extreme temperatures until it emits a bright light visible to the naked eye, but the heat is primarily contained within the midsection of the graphene, leaving the surrounding structure undamaged.
The graphene light bulb also expresses a characteristic that makes it ideal for photonic computing.
“One of the most important properties of graphene is that it heats very fast and then cools very fast,” explains Kim. In effect, it acts as a super fast binary code, making it ideal for photonic computing.
Kim expects that the speed could reach 10 gigahertz or more, possibly up to 100. At that rate, according to Kim, a photonic computer could download all of the first seven episodes of the Star Wars film series in one second
The research is still in its very early stages, but with a collaborative effort from academia and the computer industry, Kim foresees that transparent, flexible displays using the new technology could be just five years away.
“Within 10 years, we can make a photonic circuit using graphene,” he asserts, with every confidence that practice, persistence, and teamwork will pay off.