Japan Semiconductor Innovation 50     (D-1 1950s)

In 1957, Leo Esaki of Sony (then Tokyo Tsusin Kogyo -Tokyo Communication Iindustry) discovered a negative resistance characteristics in the current-voltage characteristics of very highly doped PN junction, and he demonstrated that it was a tunnel phenomenon predicted by quantum theory.
This result was reported at the fall conference of the Physical Society of Japan in the same year and also at the international conference in Brussels next year. This report was highly valued by Shockley, who was the inventor of transistor.
In 1973, the Nobel Prize for Physics was granted to this accomplishment.
Since the negative resistance characteristics can be applied to high frequency oscillation, amplification, fast switching, etc., the diodes using various materials, such as germanium, Si, and InSb, were developed, and they were called "Esaki diodes" or "tunnel diodes".

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