The Nobel Prize in Physics 2014

October 7, 2014

"The Nobel Prize in Physics 2014 was awarded jointly to Isamu Akasaki, Hiroshi Amano and Shuji Nakamura "for the invention of efficient blue light-emitting diodes which has enabled bright and energy-saving white light sources".

Isamu Akasaki, Meijo University,Japan

Hiroshi Amano, Nagoya University, Japan

Shuji Nakamura, University of California, USA

"Light-emitting diodes (LEDs) are narrow-band light sources based on semiconductor components, with wavelengths ranging from the infrared to the ultraviolet. The first LEDs were studied and constructed during the 1950s and 1960s in several laboratories. They emitted light at different wavelengths, from the infrared to the green. However, emitting blue light proved to be a difficult task, which took three more decades to achieve. It required the development of techniques for the growth of high-quality crystals as well as the ability to control p-doping of semiconductors with high bandgap, which was achieved with gallium-nitride (GaN) only at the end of the 1980s. The development of efficient blue LEDs also required the production of GaN-based alloys with different compositions and their integration into multilayer structures such as heterojunctions and quantum wells. The invention of efficient blue LEDs has led to white light sources for illumination. When exciting a phosphor material with a blue LED, light is emitted in the green and red spectral ranges, which, combined with the blue light, appears as white. Alternatively, multiple LEDs of complementary colours (red, green and blue) can be used together. Both of these technologies are used in today's high-efficiency white electroluminescent light sources. These light sources, with very long lifetimes, have begun to replace incandescent and fluorescent lamps for general lighting purposes. Since lighting represents 20-30% of our electrical energy consumption, and since these new white light sources require ten times less energy than ordinary light bulbs, the use of efficient blue LEDs leads to significant energy savings, of great benefit to mankind. This year’s Nobel Prize in Physics honours the inventors of efficient blue LEDs: I. Akasaki, H. Amano and S. Nakamura."

Full version: http://www.nobelprize.org/nobel_prizes/physics/laureates/2014/advanced-physicsprize2014_2.pdf

image source: 2014 Nobel Prize in Physics: Invention of efficient blue light-emitting diodes