Nobel Prize for Physics Goes to Researchers of Blue LEDs

Despite the best efforts of scientists in academia and the lighting industry, developing a blue LED remained a challenge for three decades. Three Japanese scientists just received the Nobel prize for succeeding in that effort.

The men behind the technology that enabled the rapid development of LED lighting for broadcast and film production were awarded the Nobel Prize for Physics on Nov. 7.

Isamu Akasaki, Hiroshi Amano and Shuji Nakamura were all working on a blue LED in Japan in the 1990s. At that time, red and green LEDs had already existed for decades, but the blue color proved elusive. The three men awarded the Nobel Prize developed the first blue LED.

Isamu Akasaki, Hiroshi Amano and Shuji Nakamura spent decades developing a blue LED. Their work earned them this year's Nobel Prize for Physics.

It is the combination of red, green and blue light together that creates white light. Red and green were not enough. Without blue LEDs, white lighting could not exist. With it, a range of new products were enabled — ranging from common home light bulbs, full-color displays and color-precise LED lighting fixtures for television and film production.

The work of the Nobel Laureates led to the creation of the new energy-efficient and environmentally friendly white light source — an invention that uses less energy, burns cooler and lasts longer compared to traditional incandescent lighting. Despite considerable efforts in both the scientific community and within industry, the blue LED had remained a challenge for three decades. The three men succeeded where others had failed.

In the 1990s, Isamu Akasaki worked together with Hiroshi Amano at the University of Nagoya, while Shuji Nakamura was independently employed at Nichia Chemicals, a small company in Tokushima.

LEDs emit light when electrons pass through layers of semiconducting material. To make LEDs glow as a blue color, the researchers had to create a new material. Drs. Akasaki, Amano and Nakamura made blue LEDs out of the element gallium. The key challenge was to grow high-quality crystals of gallium nitride — the semiconductor of choice for producing blue light. The process had been frustratingly difficult.

In 1986, Akasaki and Amano, who was then his graduate student, succeeded in growing the crystals on a substrate of sapphire coated with aluminum nitride. They found their properties were enhanced when they were scanned with an electron beam.

Meanwhile, Nakamura, working independently at Nichia, a chemical engineering and manufacturing company, succeeded in growing his own crystals, improving on Akasaki and Amano’s method. In 1992, he went on to invent the first efficient blue-light laser, which is now the heart of Blu-Ray disc players. He was awarded the Millennium Technology Prize of U.S. $1,578,252 in 2006.

Nakamura left Nichia in 1999 to join the University of California in Santa Barbara. Two years later, in a shocking challenge to the Japanese traditions of subservience, he sued the company for U.S. $193 million at the time, saying he deserved a share of royalties for his inventions.

Nichia had given him only $200 for his contributions to the company. In 2005, he and the company settled for a payment of about U.S. $8.1 million. Nakamura told Nikkei News he was dissatisfied with the amount, but had accepted it on advice of his lawyer.

The three Nobel Prize winning scientists will split a prize of $1.1 million, to be awarded in Stockholm on Dec. 10. Dr. Akasaki, 85, of Meijo University and Nagoya University, and Dr. Amano, 54, of Nagoya University, are Japanese citizens. Dr. Nakamura, 60, is an American citizen.

Few Nobel Prize winners have lived to see such fundamental change come from their inventions. White LED lamps are constantly being improved, getting more efficient with higher luminous flux (measured in lumen) per unit electrical input power (measured in watts). 

When current flows across a diode, the negative and positive electrons move in opposite directions. When a free electron finds a 'hole', (positive electron) it falls into it, losing energy. This energy is emitted in the form of a light proton, the basic principle of LEDs. Source: www.howstuffworks.com

When current flows across a diode, the negative and positive electrons move in opposite directions. When a free electron finds a 'hole', (positive electron) it falls into it, losing energy. This energy is emitted in the form of a light proton, the basic principle of LEDs. Source: www.howstuffworks.com

The most recent record is just over 300 lm/W, which can be compared to 16 for regular light bulbs and close to 70 for fluorescent lamps. As about one fourth of world electricity consumption is used for lighting purposes, the LEDs contribute to saving the Earth’s resources.

For the same amount of energy consumption, LED bulbs produce four times the light of a fluorescent bulb and nearly 20 times the light of a standard incandescent bulb.

Materials consumption is also diminished as LEDs last up to 100,000 hours, compared to 1,000 for incandescent bulbs and 10,000 hours for fluorescent lights. The LED lamp holds great promise for increasing the quality of life for over 1.5 billion people around the world, who lack access to electricity grids. Due to low power requirements, it can be powered by cheap local solar power.

The invention of the blue LED is now only twenty years old, but it has already contributed to create white light in an entirely new manner to a wide range of people and industries.

In its announcement, the academy recalled Alfred Nobel’s desire that his prize be awarded for something that benefited humankind, noting that one-fourth of the world’s electrical energy consumption goes to producing light. This, it said, was a prize more for invention than for discovery.

Frances Saunders, president of the Institute of Physics, a worldwide scientific organization based in London, agreed with those sentiments. Noting that 2015 is the International Year of Light, she said, “This is physics research that is having a direct impact on the grandest of scales, helping protect our environment, as well as turning up in our everyday electronic gadgets.”

The work of the laureates is the latest step in an evolution that began with Thomas Edison burning out light-bulb candidates in his Menlo Park laboratory in the late 19th century. Incandescent bulbs use electricity to produce heat, a glowing filament, that emits a comparatively small amount of light; fluorescent lights use a glowing gas, emitting both heat and light.

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