astronomy

Leo Esaki

Leo Esaki is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Leo Esaki rather than just read about it. In short: Leo Esaki (born March 12, 1925) is a Japanese physicist who shared the 1973 Nobel Prize in Physics with Ivar Giaever and Brian Josephson for his work on tunneling in semiconductors, which led to his invention of the tunnel diode that exploits this phenomenon. His research was done when he was with Sony.

Key takeaways

Leo Esaki belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Leo Esaki to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Leo Esaki from memory before moving on to harder problems.

Reference excerpt

Leo Esaki (born March 12, 1925) is a Japanese physicist who shared the 1973 Nobel Prize in Physics with Ivar Giaever and Brian Josephson for his work on tunneling in semiconductors, which led to his invention of the tunnel diode that exploits this phenomenon. His research was done when he was with Sony. He has also contributed in being a pioneer of semiconductor superlattices. Since the death of Yoichiro Nambu in 2015, Esaki is currently the oldest Japanese Nobel laureate.

Biography Leo Esaki was born on March 12, 1925, in Osaka, Japan. Esaki studied physics at Tokyo Imperial University (now the University of Tokyo), where he received his B.S. in 1947, and his Ph.D. in 1959. After graduating in 1947, he joined the Kobe Kogyo Corporation, before becoming chief physicist at Tokyo Tsushin Kogyo (now Sony) in 1956. In 1960, Esaki moved to the United States to join the Thomas J. Watson Research Center of IBM, where he was appointed an IBM Fellow in 1967. In 1992, he returned to Japan, where he subsequently served as President of the University of Tsukuba until 1998.

Research

Tunneling In 1957, Esaki recognized that when the p–n junction width of germanium is thinned, the current–voltage characteristic is dominated by the influence of the tunnel effect. As a result, he discovered that as the voltage is increased, the current decreases inversely, indicating negative resistance. This discovery was the first demonstration of solid tunneling effects in physics, and it was the birth of the first quantum electronic device, the tunnel diode.

Superlattices In 1969, Esaki predicted that semiconductor superlattices will be formed to induce a differential negative-resistance effect via an artificially one-dimensional periodic structural changes in semiconductor crystals. His unique "molecular-beam epitaxy" thin-film crystal growth method can be regulated quite precisely in ultrahigh vacuum. A 1987 comment by Esaki regarding the original paper notes:

"The original version of the paper was rejected for publication by Physical Review on the referee's unimaginative assertion that it was 'too speculative' and involved 'no new physics.' However, this proposal was quickly accepted by the Army Research Office..."

In 1972, Esaki realized his concept of superlattices in III-V group semiconductors. Later, this concept influenced many fields like metals and magnetic materials.

Family Esaki's daughter, Anna Esaki, is married to Craig S. Smith, former Shanghai bureau chief of The New York Times and China bureau chief of The Wall Street Journal.

Esaki's "five don'ts" rules At the 1994 Lindau Nobel Laureate Meetings, Esaki suggested a list of "five don'ts" which anyone in realizing their creative potential should follow. Two months later, the chairman of the Nobel Committee for Physics Carl Nordling incorporated the rules in his own speech.

Don't allow yourself to be trapped by your past experiences. Don't allow yourself to become overly attached to any one authority in your field – the great professor, perhaps. Don't hold on to what you don't need. Don't avoid confrontation. Don't forget your spirit of childhood curiosity.

Recognition

Awards

Memberships

Honorary degrees

Commemoration In recognition of three Nobel laureates' contributions, the bronze statues of Shin'ichirō Tomonaga, Leo Esaki, and Makoto Kobayashi were set up in the Central Park of Azuma 2 in Tsukuba in 2015.

See also Resonant-tunneling diode List of Japanese Nobel laureates List of Nobel laureates affiliated with the University of Tokyo

Notes

References

Further reading Large scale integrated circuits technology: state of the art and prospects, proceedings of the NATO Advanced Study Institute on "Large Scale Integrated Circuits Technology: State of the Art and Prospects," Erice, Italy, July 15–27, 1981 / edited by Leo Esaki and Giovanni Soncini (1982) Highlights in condensed matter physics and future prospects / edited by Leo Esaki (1991)

External links Media related to Leo Esaki at Wikimedia Commons

Leo Esaki on Nobelprize.org including the Nobel Lecture, December 12, 1973 Long Journey into Tunnelling IBM record IEEE History Center – Leo Esaki. Retrieved July 19, 2011 from Leo Esaki - Engineering and Technology History Wiki Sony History – The Esaki Diode. Retrieved August 5, 2003 from Sony Global | Sony History Freeview video 'An Interview with Leo Esaki' by the Vega Science Trust

Illustrations

Worked examples

Example 1 — a first encounter with Leo Esaki

Start with the simplest possible case. Write down what Leo Esaki claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Leo Esaki before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Leo Esaki ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Leo Esaki

In research: Leo Esaki appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Leo Esaki in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Leo Esaki is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1925 births, 20th-century Japanese inventors, 20th-century Japanese physicists, so understanding it makes those chapters shorter.
In everyday life: Look for Leo Esaki outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Leo Esaki in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Leo Esaki means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Leo Esaki out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Leo Esaki in simple terms?

Why does Leo Esaki matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Leo Esaki?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Leo Esaki.