Leo Esaki (Esaki), Leo( Japanese physicist, Nobel Prize in Physics, 1973)
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Biography Leo Esaki (Esaki), Leo
March 12, 1925
Japanese physicist Leo Esaki was born in Osaka, the son of architect Soihiro Esaki and Niek Ito He studied at the University of Tokyo, after which in 1947. Master of Science degree. After working several years in the corporation 'Kobe Kogyo' in 1956. E. transferred to the Corporation 'Sonya' in Tokyo, where he led a small research group. Simultaneously, he continued to work on his thesis.
. Classical physics says that the electrical circuit, broken the barrier of the insulator, the current flow is not quantum mechanics allows for a slightly different situation if the barrier is narrow enough, the electrons can 'tunnel' through it
. This sub-barrier passage is because the position of the electron can not be determined exactly, and hence, there is always some probability that an electron will be on the other side of the barrier. The thinner the barrier, the higher the probability of tunneling. Although this effect was predicted in the early 30-ies. But by the mid 50-ies. he has not yet been proved experimentally.
While working on his doctoral thesis, E. decided to try to verify the effect of tunneling in semiconductors by his research group called semiconductors such materials, . as silicon and germanium number of carriers in them is relatively small, . and within certain limits it can regulate, . changing the appropriate concentration of impurities.,
. and his colleagues worked with the United diodes, in which adjacent areas in a semiconductor doped with electrically active impurities of opposite polarity. Diode freely conducts current in one direction, and the connection is a barrier, did not permit it in the opposite. The barrier is formed when the content of the charge carriers near the junction is depleted. With increasing concentration of impurities the width of the depletion region decreases. Group E. managed to create diodes with very high concentrations of impurities. This created the diodes with extremely narrow passages and a high probability of tunneling E. showed that the electrical characteristics of such diodes are consistent with the ideas of quantum mechanics.
Investigating the properties of such diodes, E. discovered that some of these volt-ampere characteristics (dependence of current on voltage) is as 'vague'. If the tunneling currents in the diodes are large, the resistance of the diodes becomes negative in a limited range of changes in the current voltage across the diode decreases with increasing current (in the usual resistor current is proportional to voltage). Chain with such a negative resistance can generate high-frequency oscillations. E. developed diodes with even greater concentration of impurities and significantly higher (in absolute value) negative resistance. Such tunneling diodes (Esaki diodes) with a width of transitions in only ten billionth of a meter (thirty atoms) immediately after the creation of their first samples in 1957. could be used for generating and detecting high-frequency signals. Effect of tunneling helped to understand the properties and behavior of semiconductors and superconductors. E. presented his doctoral dissertation on the tunneling phenomena in semiconductors, University of Tokyo and in 1959. received the degree of Doctor of Science.
The following year he became a member of the research laboratories of corporations 'International business machine' (RBM) in the U.S., where he focused research on semiconductor physics. In 1965, Mr.. E. was made a member of IBM, ie. reached the highest position in the scientific hierarchy of the firm. Working at IBM, he began pioneering studies of semiconductor superreshetok, ie. complex structures obtained by deposition of extremely thin layers of different semiconductors, forming a single structure, in a single chip. The experiments showed that superreshetki possess such physical properties that turned out to be an ideal tool for understanding the effects in solid state physics. They will create a high-speed computer circuits with lower power consumption than currently common silicon. Experts believe that the 90-ies. superreshetochnye materials will be the most important components of high-speed computers.
E. received the Nobel Prize in physics in 1973. with Ivor Ivar Giaever 'for the experimental discovery of tunneling phenomena in semiconductors and superconductors'. (The other half received the award, Brian D. Josephson also for his work on tunneling). 'In a series of brilliant experiments and calculations you have studied various aspects of the phenomenon of tunneling in solids, - said, referring to three Nobel laureates, Stig Lundqvist of the Royal Swedish Academy of Sciences. - Your discoveries have paved the way to new areas of research and achieve a deeper understanding of the behavior of electrons in semiconductors and superconductors, macroscopic quantum phenomena in superconductors'. In his speech, Lundquist also noted that the opening E., Ivar Giaever and Josephson are closely linked, as the 'pioneering work E. served as the basis and impetus for the immediate opening Ivar Giaever, Ivar Giaever and work ... led to the theoretical predictions of the Josephson '.
In reply, E. said: "Brian Josephson, Ivar Giaever Ivor and I brought up in completely different cultures ... We are in some way symbolize the fact that in physics, as in other sciences, there is no national or racial boundaries ... ' 'The fundamental knowledge about nature - he continued - one of the greatest treasures ... and it belongs to all mankind ... In our world there are many high barriers - between nations, races and religions. Unfortunately, some of them are broad and strong. But I hope, moreover, I am confident that we will find a way to allow free and easy to tunnel through these barriers, and rally the world in a whole '.
Working in the U.S., E. retained Japanese citizenship. In 1959, Mr.. He married Misako Araki, and they had two daughters and a son.
E. elected as a member of the Japan Academy, the American Academy of Arts and Sciences, foreign member of the National Academy of Sciences of the USA. Since 1967. E. is the director of IBM. He was awarded honorary degrees from Japanese school Dosida and the Polytechnic University of Madrid. He was awarded Morris H. Liebmann Institute of Radio Engineers (1961), Medal Stuart Ballantyne Franklinovskogo Institute (1961) and the Japanese Order of Culture (1974).