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The report in 1958 of the invention of the tunnel diode by Sony Corp.'s Leo Esaki created almost as much excitement as the announcement of the transistor by Bell Labs a decade earlier. This may have been because tunneling was a fundamental idea from quantum physics, and here it was in a simple p-n junction. Here was a super-fast device with switching speeds that left most transistors in the dust. As the fame of the tunnel diode spread through the electronics world, the device often took on the name of its inventor. It was widely known as the Esaki Diode. And the development earned Esaki a Nobel Prize in 1973. Before the award of that Nobel, the world was shaken when it learned that Esaki was leaving Sony in Japan to join IBM in NewYork State, an almost unprecedented happening.
Japanese companies, especially large and reputable ones like Sony, were known for lifetime employment. Once you earned employment at an outfit like Sony, you knew that you would stay there forever or, at least, till you retired or died. So itwas almost unheard of for somebody to leave, especially a high-ranking individual like Leo Esaki.
So remarkable was Esaki's departure that both Sony and IBM issued press releases indicating that Esaki's move had the blessings of both companies and he was leaving under the most honorable circumstances. (Esaki is now president of the University of Tsukuba in Japan.)
Switching times for the Esaki Diode were in the picosecond range while most transistors at the time were really stepping along if they managed milliseconds. This was clearly the device for microwave circuitry and new computer circuits, especially as a fast switch.
Just two problems
There were, however, two small problems. First, nobody was manufacturing the tunnel diode just yet. So you couldn't design those super-fast circuits that many customers wanted. But surely, any day now, somebody would announce that he had tunnel...