ASU professor researches LED technology
ASU physics professor Fernando Ponce, like many university professors, is more than just an educator; he’s a scientist on the cutting edge of innovation.
Ponce has been working to maximize the efficiency of LED technology, which is used in a variety of everyday devices from Christmas tree lights and cell phones to flashlights and traffic signals, for more than 20 years.
Professor Peter Bennett, the chair of ASU’s Department of Physics, said Ponce is a truly exceptional scientist.
“One way that he stands out, is that he really bridges the gap between fundamental physics principles and applied, practical things like lighting,” Bennett said. “You will find, in the spectrum of physics scientists, that some of them are focused on the very textbook fundamentals of the field. You’ll also find some over on the more applied side. (Ponce) is in the middle and makes the bridge between them.”
Ponce has worked with some of the best researchers in his field, and a few of his collaborators were honored with the Nobel Prize in Physics earlier this month.
The Nobel Prize in Physics was awarded on Oct. 7 to Japanese scientists Isamu Akasaki, Hiroshi Amano and Shuji Nakamura, all of whom Ponce has worked with closely over the years for their invention of blue LEDs and cultivation of white LEDs.
According to a press release by the Royal Swedish Academy of Sciences, the scientists were recognized “for the invention of efficient blue light-emitting diodes which has enabled bright and energy-saving white light sources.”
However, Ponce said although Akasaki, Amano and Nakamura made the fundamental breakthrough in inventing the blue LED, the huge research effort regarding the devices has been executed by a community made up of thousands of scientists.
“People have been trying to produce light since a long time ago,” Ponce said. “We started first with fire, candles, and eventually the incandescent light was invented. There was a progression, and every time (a new form of light production came about), the ability to produce light using some amount of energy became more efficient.”
He said the search for a maximum-efficiency light source has been going on for almost a century. However, the search was revolutionized in 1993, when Japanese engineer Shuji Nakamura travelled to Silicon Valley to show Hewlett Packard executives a small device that emitted “blinding” light when electrical current passed through it.
Confused about how such a powerful emission of light could be created from such a small piece of semi-conductor material, the head of Hewlett Packard took the Japanese device to Xerox PARC in Palo Alto, California, for analysis. This is where Ponce, then a Xerox employee, was introduced to Gallium Nitride light production for the first time.
After close examination of the device — a light-emitting diode — Ponce discovered that the compound Gallium Nitride was being used to emit a unique blue light and that intrigued him enormously.
“They succeeded in producing a very bright light-emitting diode, but at that point we didn’t know what it was,” he said. “We had to figure out how they did it. It was done by engineers who were looking for a recipe, and they found the recipe, but nobody understood the meaning of that.”
Ponce said he had been familiar with other types of LEDs before he was introduced to the Japanese device, but they were only capable of producing red or amber light. LEDs of the blue variety were entirely unheard of at the time.
Since being introduced to blue LEDs in 1993, Ponce has dedicated most of his professional career to investigating the physics behind the technology. He has also studied white LEDs since they were developed through the manipulation of blue LEDs more recently.
Ponce said white LEDs are reaching efficiencies “very close to their physical limit,” but his goal is to perfect Gallium Nitride light production so that it yields light with 100 percent efficiency. He wants to be able to convert electricity into light without wasting any energy at all, he said.
“(The efficiency of these white LEDs) is a tremendous achievement for humanity,” Ponce said. “We need to use this energy to illuminate our lives.”
He said using more energy-efficient LEDs would help to preserve the environment by reducing unnecessary energy use, which often has damaging effects on the natural world.
Ponce has also stepped into the world of clean energy production. He said he and other researchers in his lab at ASU are working to create high-efficiency solar cells by effectively “reversing” blue LED technology.
“As well as creating light from energy, we now want to create energy from light,” he said.
Alec Fischer, a research scientist who works with Ponce in his lab, said he enjoys working with such an innovative scientist and thinks Ponce’s years of experience make him a great teacher to have at the University.
“He worked at Xerox and HP, where most of the initial development of these (blue LED) semiconductors started,” Fischer said in an email. “He then brought this knowledge and shared his experiences to the students.”
Fischer said the atmosphere in Ponce’s lab is a “mixture of industry and academia,” in which students have ample opportunity to hone their skills and solve problems.
Hongen Xie is a doctorate student who works closely with Ponce, and he also said the Ponce lab is a great learning environment. He said he feels the research being done there is among the most important in the field.
“This technology has already started to change our lives,” Xie said in an email. “Almost all the blue light sources we are seeing today are based on Gallium Nitride LEDs."
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