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Walter Hermann Schottky
Walter Hermann Schottky.
1886 - 1976.

Walter Hermann Schottky was born in Zurich, Switzerland, on July 23, 1886.
His father, Friedrich, was a university mathematician.

Walter grew up in Marburg and Berlin, Germany, due to his fathers' moves for his work. Walter attended schools in both places, completing his high school diploma in 1904. He entered the Humboldt University in Berlin later that year, where he studied physics. In Humboldt Walter earned his doctorate under Max Planck, working on the Special Theory of Relativity, which Albert Einstein had announced only seven years earlier.

Walter went to the Jena University, Thuringia, Germany (now the Friedrich Schiller University of Jena) for a couple of years before moving to the Siemens Industrial Research Laboratories in Berlin. In 1920 he moved to Wurzburg University, where he qualified as a university lecturer.

While Walter was at Siemens he independently invented the superhet, typically credited to Edwin Armstrong, in 1918. Also he further developed his interests in electronic valves. He produced a number of discoveries and inventions during this time. He invented the screen-grid valve in 1915, and in 1919 he invented the tetrode, the first multigrid vacuum valve. A tetrode contains two grids, the basic one and a second grid called the screen. The screen prevents the valve from producing unwanted oscillations.

in 1924 Walter, along with Erwin Gerlach, invented the Ribbon Microphone. This consisted of an extremely thin concertina ribbon of aluminum placed between the poles of a permanent magnet to generate voltages by electromagnetic induction when the ribbon was excited by sound waves. They also devised a ribbon loadspeaker as well, simply by reversing the physical effects of the microphone.

In 1938 Walter created a theory that explained the rectifying behaviour of a metal-semiconductor contact as dependent on a barrier layer at the surface of contact between the two materials. The metal semiconductor diodes later built on the basis of this theory are called Schottky barrier diodes. The importance of these diodes being the speed at which they can be switched off from the saturated state. This speed is enabled by the fact that they are made from a junction between a metal and a semiconductor instead of a junction between two pieces of a semiconductor. Walter also discovered that the current emitted from the metal cathode into the vacuum in a valve depends on the metals' work function, and that this function was lowered from its normal value by the presence of image forces and by the electric field at the cathode. This effect later became known as the Schottky effect, and would later be extended to semiconductor devices to revolutionise their construction. Walter continued to produce predictions and inventions that transformed the field of electronics until his retirement.

After retirement, Walter spent the rest of his life in Pretzfeld, Germany, where he died on March 4, 1976 at the age of 90. His death came just two years after his former employer, Siemens, had begun commercially manufacturing Schottky diodes for microwave use. Although he was known as a modest and selfless character who avoided the center stage, Walter Hermann Schottky had changed the industry that controls almost every aspect of modern daily life.

Some of Walter H Schottkys' Achievements and Honours:

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