Isamu Akasaki

Isamu Akasaki
Akasaki in 2011
Isamu Akasaki
Born	30 1, 1929
Birthplace	Chiran, Kagoshima Prefecture, Empire of Japan
Died	Template:Death date and age Nagoya, Aichi Prefecture, Japan
Nationality	Japanese
Occupation	Electronics engineer, physicist, materials scientist
Known for	Invention of blue and white LEDs using gallium nitride
Education	Nagoya University (Ph.D., 1964)
Spouse(s)	Ryoko Akasaki
Awards	Nobel Prize in Physics (2014), Kyoto Prize (2009), Order of Culture (2011)

Isamu Akasaki (Template:Lang, Akasaki Isamu; January 30, 1929 – April 1, 2021) was a Japanese electronics engineer and materials scientist whose decades-long research into gallium nitride (GaN) semiconductors fundamentally transformed modern lighting technology. Working at a time when many researchers had abandoned GaN as a viable material, Akasaki persisted in developing techniques that ultimately enabled the creation of the first bright blue light-emitting diode (LED) in 1989. This achievement, which completed the trio of primary-color LEDs necessary to produce white light, opened the way for the energy-efficient LED lighting that became ubiquitous in the 21st century. For this work, Akasaki was awarded the 2014 Nobel Prize in Physics, shared with his former doctoral student Hiroshi Amano and the independent researcher Shuji Nakamura, "for the invention of efficient blue light-emitting diodes which has enabled bright and energy-saving white light sources." Over the course of his career, Akasaki held positions at Matsushita Electric Industrial (now Panasonic), Nagoya University, and Meijo University, where he continued his research until his final years. He received numerous accolades throughout his life, including the Kyoto Prize, the Order of Culture from the Japanese government, and fellowship in the Institute of Electrical and Electronics Engineers (IEEE).

Early Life

Isamu Akasaki was born on January 30, 1929, in Chiran, a town in Kagoshima Prefecture on the southern Japanese island of Kyushu. Chiran was a rural community in what was then the Empire of Japan, located in the southern part of the Satsuma Peninsula. Akasaki grew up in this region during a period of significant political and social change in Japan, as the country moved through the militaristic era of the 1930s and into the devastation of World War II.

Details of Akasaki's childhood and family background remain relatively sparse in the public record, though his upbringing in southern Kyushu placed him far from the major industrial centers of Japan. Despite this geographic remoteness, Akasaki developed an early interest in science and technology that would guide his academic pursues. The post-war period in Japan, marked by reconstruction and rapid industrialization, provided a backdrop against which Akasaki pursued higher education in the sciences.

Education

Akasaki pursued his higher education at Kyoto University, one of Japan's most prestigious academic institutions, where he studied electrical engineering. After completing his undergraduate studies at Kyoto University, he went on to earn his doctoral degree from Nagoya University in 1964, with a thesis focused on semiconductor research. His doctoral work laid the groundwork for the semiconductor physics research that would define his career. The decision to pursue graduate studies at Nagoya University proved consequential, as it established his long association with the institution where much of his most significant research would later be conducted.

Career

Early Career at Matsushita Electric

After completing his initial studies, Akasaki joined Matsushita Electric Industrial Company (later known as Panasonic), one of Japan's largest electronics corporations. He worked in the company's research laboratories, where he began investigating compound semiconductors and their potential applications. During his tenure at Matsushita, Akasaki gained practical experience in semiconductor technology and materials science within an industrial research setting. This period of industry work provided him with both technical expertise and an understanding of the practical challenges involved in semiconductor development.

At Matsushita, Akasaki began to focus his attention on gallium nitride (GaN), a III-V semiconductor material that had been identified as theoretically promising for producing blue light. Blue LEDs were considered the missing component needed to complete the color spectrum of solid-state lighting—red and green LEDs had already been developed, but without blue, white LED light could not be produced. However, GaN was notoriously difficult to work with. The material was plagued by problems with crystal quality, and most researchers in the field had concluded that it was not a viable path forward for optoelectronic devices. Many had turned instead to zinc selenide and other materials as more promising candidates for blue light emission.

Research at Nagoya University

In 1981, Akasaki left Matsushita Electric and returned to academia, joining the faculty of Nagoya University as a professor in the Department of Electronics. This move proved to be a turning point in both his career and the history of LED technology. At Nagoya University, Akasaki established a research group dedicated to GaN semiconductor research at a time when the material was largely considered a dead end by the broader scientific community.

One of the central problems facing GaN research was the production of high-quality crystal films. GaN crystals grown using existing methods contained large numbers of defects, which degraded the material's electronic and optical properties. Akasaki and his team worked to develop improved crystal growth techniques, eventually achieving a significant breakthrough using metalorganic vapor phase epitaxy (MOVPE) to grow GaN on sapphire substrates. By developing a low-temperature buffer layer technique using aluminum nitride (AlN), Akasaki and his group were able to produce GaN films of substantially higher quality than had previously been possible.

A pivotal figure in this research was Hiroshi Amano, who joined Akasaki's laboratory as a graduate student at Nagoya University. Together, Akasaki and Amano tackled the problem of p-type doping in GaN—the process of introducing impurities to create a semiconductor with a surplus of positive charge carriers (holes). Achieving p-type conductivity in GaN had been one of the most persistent obstacles in the field. In 1989, Akasaki and Amano succeeded in creating p-type GaN using magnesium doping combined with low-energy electron beam irradiation (LEEBI), a technique that activated the magnesium acceptors in the crystal. This achievement enabled the creation of the first GaN p–n junction blue LED, a device that emitted bright blue light and represented a fundamental breakthrough in semiconductor technology.

The significance of this achievement was immense. With the demonstration of a viable p–n junction blue LED, Akasaki and Amano had shown that GaN was indeed a workable material for optoelectronic devices, overturning years of skepticism within the research community. Their work opened the floodgates for further research into GaN-based devices, including not only LEDs but also laser diodes and high-power electronic components.

Following the initial blue LED breakthrough, Akasaki and his collaborators continued to refine their techniques and improve the performance of GaN-based devices. They developed high-brightness blue LEDs and explored the broader family of Group III nitride semiconductors, including indium gallium nitride (InGaN), which allowed for the tuning of emission wavelengths across a wider range of the visible spectrum. These developments were essential steps toward the creation of efficient white LED lighting, which combined blue LEDs with phosphor coatings to produce broad-spectrum white light.

Career at Meijo University

In 1992, Akasaki took on an additional appointment at Meijo University in Nagoya, where he became a professor and continued his GaN research. He maintained affiliations with both Meijo University and Nagoya University for much of the remainder of his career, holding the title of Distinguished Professor and University Professor at Meijo University and Professor Emeritus at Nagoya University.

At Meijo University, Akasaki continued to advance the state of the art in nitride semiconductor research. His laboratory remained a center for GaN studies, training a new generation of researchers in the field. The work conducted at both Meijo and Nagoya Universities contributed to the rapid maturation of GaN technology through the 1990s and 2000s, as blue and white LEDs moved from laboratory curiosities to commercially viable products with enormous energy-saving potential.

The Nobel Prize committee noted in its 2014 citation that the invention of efficient blue LEDs had enabled "bright and energy-saving white light sources," estimating that LED lighting had the potential to dramatically reduce global electricity consumption for lighting purposes. Since roughly one quarter of world electricity consumption was used for lighting, the transition from incandescent and fluorescent technologies to LEDs represented a contribution with far-reaching environmental and economic implications.

Independent and Parallel Work

While Akasaki and Amano conducted their research at Nagoya University, Shuji Nakamura, working independently at Nichia Corporation in Tokushima, Japan, made parallel advances in GaN technology in the early 1990s. Nakamura developed his own methods for growing high-quality GaN crystals and achieving p-type doping, and he produced commercially viable high-brightness blue LEDs. The 2014 Nobel Prize recognized the contributions of all three researchers—Akasaki, Amano, and Nakamura—acknowledging the distinct but complementary paths that led to the development of efficient blue LEDs.

Personal Life

Isamu Akasaki was married to Ryoko Akasaki. He maintained a relatively private personal life throughout his career, devoting most of his professional energy to his research at Nagoya and Meijo Universities.

Akasaki died on April 1, 2021, in Nagoya, Aichi Prefecture, Japan, at the age of 92. The cause of death was reported as pneumonia. His death was widely noted in scientific and general media, with tributes highlighting his persistence in pursuing GaN research when most of the scientific community had written off the material. In a tribute published in Nature Photonics, colleagues described his decades of commitment to GaN semiconductors and the transformative impact of his work on modern lighting technology.

Recognition

Akasaki received numerous awards and honors throughout his career, reflecting the significance of his contributions to semiconductor science and technology.

In 2004, he received the Takeda Award. In 2009, Akasaki was awarded the Kyoto Prize in Advanced Technology, one of Japan's most prestigious international awards for outstanding contributions to science, technology, and the arts. The prize, administered by the Inamori Foundation, recognized his pioneering work in GaN-based optoelectronic devices.

In 2011, Akasaki received the Order of Culture from the Emperor of Japan, the country's highest cultural distinction, awarded for outstanding contributions to Japanese culture and science.

Akasaki was named an IEEE Fellow in 1999, recognizing his contributions to the field of electrical and electronics engineering.

In 2006, he received the John Bardeen Award from The Minerals, Metals & Materials Society (TMS), an honor named after the two-time Nobel laureate in physics.

He was elected as a foreign associate of the National Academy of Engineering of the United States, recognizing the international impact of his engineering contributions.

The crowning recognition came on October 7, 2014, when the Royal Swedish Academy of Sciences announced that Akasaki, Amano, and Nakamura would share the Nobel Prize in Physics. In a telephone interview conducted by Nobel Media shortly after the announcement, Akasaki expressed his satisfaction at the recognition of work that had taken decades to reach fruition.

He also received the Electrochemical Society's Electronics Division Award for his contributions to solid-state science and technology.

Legacy

Akasaki's most enduring legacy lies in his role in making blue LEDs a reality, a development that the Nobel Prize committee described as having transformed lighting technology for the 21st century. Red LEDs had existed since the 1960s, and green LEDs followed in subsequent decades, but without blue LEDs, the creation of white LED light was not possible. By demonstrating that GaN could be used to produce efficient blue light emission, Akasaki and his collaborators removed the final barrier to a new era of solid-state lighting.

The practical consequences of this invention have been substantial. LED lighting consumes a fraction of the electricity required by incandescent bulbs and is more efficient than fluorescent lighting. The transition to LED-based illumination has contributed to reductions in electricity consumption and carbon emissions worldwide. Beyond general lighting, the GaN technology pioneered by Akasaki has found applications in display technology, including the backlighting of liquid crystal displays and the development of microLED displays. GaN-based laser diodes enabled the Blu-ray Disc format, and GaN semiconductors are increasingly used in power electronics for electric vehicles and telecommunications infrastructure.

Akasaki's persistence in pursuing GaN research during the years when the material was considered unpromising has been cited as an example of the importance of long-term, fundamental research. For roughly two decades, he continued his work with limited recognition and against the prevailing consensus in the semiconductor research community. The eventual vindication of his approach served as a demonstration that scientific breakthroughs often require sustained commitment in the face of skepticism.

His mentorship of Hiroshi Amano, who shared the 2014 Nobel Prize, also represents a significant contribution to the development of the field. The research group that Akasaki established at Nagoya University trained numerous scientists and engineers who went on to contribute to GaN technology and related fields of semiconductor research.

Upon the announcement of his death in April 2021, tributes came from the international scientific community recognizing his foundational role in a technology that had reshaped modern life. As Physics World noted, Akasaki's work in the late 1980s and early 1990s "led to the development of blue light-emitting diodes" that formed the basis for one of the most significant technological shifts of the early 21st century.