Isamu Akasaki (赤﨑 勇,Akasaki Isamu, January 30, 1929 – April 1, 2021) was a Japanese engineer and physicist, specializing in the field ofsemiconductor technology andNobel Prize laureate, best known for inventing the brightgallium nitride (GaN) p-n junction blueLED in 1989 and subsequently the high-brightness GaN blue LED as well.[1][2][3][4][5]
Isamu graduated from Kagoshima Prefectural Daini-Kagoshima Middle School (nowKagoshima Prefectural Konan High School) in 1946, from Seventh Higher School Zoshikan (nowKagoshima University) in 1949[11] and from Department of Chemistry, Faculty of Science,Kyoto University in 1952.[10] During his university years, he visited shrines and temples that local residents rarely visit, walked around the mountains ofShinshu during the summer vacation, enjoyed classes and enjoyed a fulfilling student era.[10] After he became a researcher, he obtained the degree ofDoctor of Engineering fromNagoya University in 1964.[14]
Akasaki started working onGaN-based blue LEDs in the late 1960s. Step by step, he improved the quality of GaN crystals anddevice structures[15] at Matsushita Research Institute Tokyo, Inc. (MRIT), where he decided to adoptmetalorganic vapor phase epitaxy (MOVPE) as the preferred growth method for GaN.
In 1981, Akasaki started afresh the growth of GaN by MOVPE at Nagoya University, and in 1985 he and his group succeeded in growing high-quality GaN on sapphire substrate by pioneering the low-temperature (LT) buffer layer technology.[16][17]
This high-quality GaN enabled them to discover p-type GaN by doping withmagnesium (Mg) and subsequent activation by electron irradiation (1989), to produce the first GaN p-n junction blue/UV LED (1989), and to achieve conductivity control of n-type GaN (1990)[18] and related alloys (1991)[19] by doping with silicon (Si), enabling the use of hetero structures and multiple quantum wells in the design and structure of more efficient p-n junction light emitting structures.
They achieved stimulated emission from the GaN firstly at room temperature in 1990,[20] and developed in 1995 the stimulated emission at 388 nm with pulsed current injection from high-quality AlGaN/GaN/GaInN quantum well device.[21] They verified quantum size effect (1991)[22] and quantum confined Stark effect (1997)[23] in nitride system, and in 2000 showed theoretically the orientation dependence of piezoelectric field and the existence of non-/semi-polar GaN crystals,[24] which have triggered today's worldwide efforts to grow those crystals for application to more efficient light emitters.
Akasaki's patents were produced from these inventions, and the patents have been rewarded as royalties. Nagoya University Akasaki Institute[25] opened on October 20, 2006. The cost of construction of the institute was covered with the patent royalty income to the university, which was also used for a wide range of activities in Nagoya University. The institute consists of an LED gallery to display the history of blue LED research/developments and applications, an office for research collaboration, laboratories for innovative research, and Akasaki's office on the top sixth floor. The institute is situated in the center of the collaboration research zone in Nagoya University Higashiyama campus.
Akasaki worked as a Research Scientist from 1952 to 1959 at Kobe Kogyo Corporation (now,Fujitsu Ltd.).[26] In 1959 he was a research associate, assistant professor, and associate professor at the Department of Electronics atNagoya University until 1964. Later in 1964, he was the Head of Basic Research Laboratory at Matsushita Research Institute Tokyo, Inc. until 1974 to later become a General Manager of Semiconductor Department (in the same institute until 1981).[citation needed] In 1981 he became a professor in the Department of Electronics at Nagoya University until 1992.[26]
From 1987 to 1990 he was a Project Leader of "Research and Development of GaN-based Blue Light–Emitting Diode" sponsored byJapan Science and Technology Agency (JST). He then led the "Research and Development of GaN-based Short-Wavelength Semiconductor Laser Diode" product sponsored by JST from 1993 to 1999. While he led this project, he was also a visiting professor at the Research Center for Interface Quantum Electronics atHokkaido University, from 1995 to 1996. In 1996 he was a Project Leader of the Japan Society for the Promotion of Science's for the "Future program" up to 2001. From 1996 he started as a Project Leader of "High-Tech Research Center for Nitride Semiconductors" atMeijo University, sponsored by MEXT until 2004. From 2003 up to 2006 he was the Chairman of "R&D Strategic Committee on the Wireless Devices Based on Nitride Semiconductors" sponsored by METI.
He continued working as a Professor Emeritus of Nagoya University, Professor of Meijo University from 1992.[26] He was also the Director of the Research Center for Nitride Semiconductors at Meijo University since 2004. He also worked as a Research Fellow at Akasaki Research Center of Nagoya University from 2001.
2006 – Outstanding Achievement Award, the Japanese Association for Crystal Growth
2007 – Honorable Lifetime Achievement Award, the 162nd Research Committee on Wide Bandgap Semiconductor Photonic and Electronic Devices, Japan Society for the Promotion of Science (JSPS)
2008 – Foreign Associate, the US National Academy of Engineering[41]
2009 –Kyoto Prize Advanced Technology, the Inamori Foundation[42]
2010 – Lifetime Professor, Meijo University
2011 –Edison Medal, the Institute of Electrical and Electronics Engineers[7]
^Isamu Akasaki; Hiroshi Amano; Masahiro Kito; Kazumasa Hiramatsu (1991). "Photoluminescence of Mg-doped p-type GaN and electroluminescence of GaN p-n junction LED".Journal of Luminescence.48–49. Elsevier BV:666–670.Bibcode:1991JLum...48..666A.doi:10.1016/0022-2313(91)90215-h.ISSN0022-2313.
^赤崎 (1964).赤崎 勇「Geの気相成長に関する研究」.CiNii (PhD Thesis) (in Japanese). National Institute of Informatics (Japan). Retrieved2022-06-27.
^Y. Ohki, Y. Toyoda, H. Kobayasi and I. Akasaki: "Fabrication and properties of a practical blue-emitting GaN m-i-s diode. Inst. Phys. Conf. Ser. No. 63, pp. 479-484 (Proc. of the 9th Intl. Symposium on Gallium Arsenide and Related Compounds, 1981).
^Amano, H.; Sawaki, N.; Akasaki, I.; Toyoda, Y. (February 3, 1986). "Metalorganic vapor phase epitaxial growth of a high quality GaN film using an AlN buffer layer".Applied Physics Letters.48 (5). AIP Publishing:353–355.Bibcode:1986ApPhL..48..353A.doi:10.1063/1.96549.ISSN0003-6951.
^Akasaki, Isamu;Amano, Hiroshi; Koide, Yasuo; Hiramatsu, Kazumasa; Sawaki, Nobuhiko (1989). "Effects of ain buffer layer on crystallographic structure and on electrical and optical properties of GaN and Ga1−xAlxN (0 < x ≦ 0.4) films grown on sapphire substrate by MOVPE".Journal of Crystal Growth.98 (1–2). Elsevier BV:209–219.doi:10.1016/0022-0248(89)90200-5.ISSN0022-0248.
^H. Amano and I. Akasaki: "Fabrication and Properties of GaN p-n Junction LED", Mater. Res. Soc. Extended Abstract (EA-21), pp.165-168, 1990, (Fall Meeting 1989)
^Murakami, Hiroshi; Asahi, Tsunemori; Amano, Hiroshi; Hiramatsu, Kazumasa; Sawaki, Nobuhiko; Akasaki, Isamu (1991). "Growth of Si-doped AlxGa1–xN on (0001) sapphire substrate by metalorganic vapor phase epitaxy".Journal of Crystal Growth.115 (1–4). Elsevier BV:648–651.Bibcode:1991JCrGr.115..648M.doi:10.1016/0022-0248(91)90820-u.ISSN0022-0248.
^Amano, Hiroshi; Asahi, Tsunemori; Akasaki, Isamu (February 20, 1990). "Stimulated Emission Near Ultraviolet at Room Temperature from a GaN Film Grown on Sapphire by MOVPE Using an AlN Buffer Layer".Japanese Journal of Applied Physics.29 (Part 2, No. 2). Japan Society of Applied Physics:L205 –L206.Bibcode:1990JaJAP..29L.205A.doi:10.1143/jjap.29.l205.ISSN0021-4922.S2CID120489784.
^Akasaki, Isamu; Amano, Hiroshi; Sota, Shigetoshi; Sakai, Hiromitsu; Tanaka, Toshiyuki; Koike, Masayoshi (November 1, 1995). "Stimulated Emission by Current Injection from an AlGaN/GaN/GaInN Quantum Well Device".Japanese Journal of Applied Physics.34 (11B). Japan Society of Applied Physics: L1517–L1519.Bibcode:1995JaJAP..34L1517A.doi:10.7567/jjap.34.l1517.ISSN0021-4922.S2CID122963134.
^Itoh, Kenji; Kawamoto, Takeshi; Amano, Hiroshi; Hiramatsu, Kazumasa; Akasaki, Isamu (September 15, 1991). "Metalorganic Vapor Phase Epitaxial Growth and Properties of GaN/Al0.1Ga0.9N Layered Structures".Japanese Journal of Applied Physics.30 (Part 1, No. 9A). Japan Society of Applied Physics:1924–1927.Bibcode:1991JaJAP..30.1924I.doi:10.1143/jjap.30.1924.ISSN0021-4922.S2CID123428785.
^Takeuchi, Tetsuya; Sota, Shigetoshi; Katsuragawa, Maki; Komori, Miho; Takeuchi, Hideo; Amano, Hiroshi; Akasaki, Isamu (April 1, 1997). "Quantum-Confined Stark Effect due to Piezoelectric Fields in GaInN Strained Quantum Wells".Japanese Journal of Applied Physics.36 (Part 2, No. 4A). Japan Society of Applied Physics:L382 –L385.Bibcode:1997JaJAP..36L.382T.doi:10.1143/jjap.36.l382.ISSN0021-4922.S2CID95930600.
^Takeuchi, Tetsuya; Amano, Hiroshi; Akasaki, Isamu (February 15, 2000). "Theoretical Study of Orientation Dependence of Piezoelectric Effects in Wurtzite Strained GaInN/GaN Heterostructures and Quantum Wells".Japanese Journal of Applied Physics.39 (Part 1, No. 2A). Japan Society of Applied Physics:413–416.Bibcode:2000JaJAP..39..413T.doi:10.1143/jjap.39.413.ISSN0021-4922.S2CID121954273.
