Dr. Leo Esaki, inventor of the Tunel diode. (Electronic World)
Close up of the device invented by Dr. Esaki as known as tunel diode.
Its feasibility had been predicted in 1929 by George Gamow -the American physicist who started the studies to explain the large Neutrino emissions due to thermonuclears explosions in solar nucleous - It was so named because its operation relied on the quantum-mechanical probability of electrons tunneling through an energy barrier they could not surmount. Therefore, it was only in 1958 through the researches of the Japanese scientist Dr Leo Esaki, working for Sony Corporation, that the first Tunnel diode could be developed in a practical way. Fig 255
Originally, an extremely abrupt junction between very highly doped P and N regions of a Gemanium matrix, to make the depletion regions of the diode very thin, on the order of a few hundreds of Angstrons, formed such semiconductor device.
In effect due to its behavior to a negative resitance, the Tunnel diode could be put to use for high-frequency amplification, oscillation or switching.
Due to its high speed in signal processing, around 100 picoseconds, manufactures foresaw many applications for such a kind of device. Fig 256
Therefore the interest in the tunnel diode waned rapidly due to the improvement in the Transistor technology as well as the birth of the integrated circuit, which was the fundamental element for the manufacturing of computer memory, originally the purpose of the device invented by Dr. Esaki.
Gaining in importance throughout the late fifities and early sixties were semiconductor devices whose operation extended to the uppermost frequency and beyond to the visible-light spectrum. Most of these emerged from compound semiconductors such as Gallium Arsenide and Indium Phosphide, which led to the invention of light emitting diode