Walter Schottky

Walter Schottky is a famous name in the fields of electronics and physics. Today, a lot of devices used in these fields bear his name, and some scientific phenomena are also named after him. Two of the most famous are the Schottky effect, where there is an irregularity in thermion emissions when inside a vacuum tube, and the Schottky defect which describes a certain crystal lattice vacancy that results from the displacement of an ion to the surface of a crystal. He has made a significant number of contributions for solid-state physics and electronics and is also known as an inventor.

Early Life and Personal Background

Born on the 23rd of July, 1886, in Zurich, Switzerland, Walter Hermann Schottky was the son of a mathematician named Friedrich Hermann Schottky who was known for working on abelian, elliptic, and the theta functions, and also for introducing Schottky’s theorem. Walter was one of two sons, and he had a sister. He was born 4 years after his father’s appointment at the University of Zurich as a professor of Mathematics. Schottky’s family had to return to Germany in the year 1892 when Friedrich Schottky was appointed with a position at the University of Marburg.

In 1904, he graduated in Berlin’s Steglitz Gymnasium. He was able to complete his B.S. degree in physics in 1908 at the Berlin University. Four years later, he was able to complete his doctorate degree also at the University of Berlin where he was under the instructions of Heinrich Rubens and Max Planck, two of the most notable names in physics during those years. Schottky’s thesis was called the Zur relativtheoretischen Energetik und Dynamik.

Career

After completing his education he taught physics as one of the professors in the University of Rostock Germany. He held this post from 1923 to 1927. Prior to his career as an academic instructor, Schottky spent his post-doctoral time at the University of Jena for two years from 1912-1914. He then held lectures at the University of Wurzburg from 1919-1923 before becoming a full professor at the University of Rostock.

After his career as a professor and a scholar, he worked as one of the industrial researchers at Siemens & Halske where he was given the chance to work in Berlin as well as Pretzfeld, the latter a rather obscure town in Bavaria where Siemens happened to have a research center. During his time there, he conducted his research on semiconductor physics which was also known back then as “dirty physics.” Unfortunately, there weren’t any products developed from his research then, but he also studied electronics where he was able to work with the vacuums which paved the way for his discoveries later on.

One of his inventions had been the ribbon microphone which he had co-invented with Erwin Gerlach. Their idea behind this invention was how a fine ribbon suspended by magnetic fields can come up with electric signals. The same concept was what led to the fruition of the ribbon loudspeaker which used the same idea but in reverse order. This invention, however, was not considered practical until high flux and permanent magnets were made more accessible in the latter years of 1930. His research on how noise comes from electron currents was also referred to as the Schrot effect, or literally, the small shot effect.

Probably one of the most noted scientific achievements or contributions by Schottky was his formula which helps compute for interaction energy between a certain point charge and another flat metal surface while the charge is at a certain distance from said surface. The interaction derived from this formula is known as the image PE or image potential energy. This work by Schottky was based on Lord Kelvin’s earlier works on thermodynamics. Today, the image PE which was determined by Schottky is now one of the standard components in models which show the barrier to motion that electrons approaching metal surfaces experience.

Apart from his contributions for scientific calculations and measurements, he also had other inventions aside from the ribbon microphone and loudspeaker. These inventions include the screen grid tube and the tetrode. He was also able to invent the screen grid tube in 1915. This was an evolution of the triode tube, and improvements in 1916 paved way to the development of the double-grid tube where the additional grid was able to reduce space charge. It was in 1919 when he was able to invent the tetrode which is known as the very first multigrid vacuum tube.

Because of his inventions, he was able to study electron transfers and he also had exposure and contributions to the development of semiconductor devices. Although he previously incorrectly suggested that field electron emission happens when a barrier is brought down to zero. The fact is that this effect is caused by wave-mechanical tunneling as explained by Nordheim and Fowler in the year 1928. Despite Schottky’s incorrect suggestion, the SN barrier has become the standard used for the tunneling barrier.

When the behavior of interfaces in semiconductor devices is studied closely, it has been discovered that they can be a special kind of diode which is known as the Schottky diode. The metal-semiconductor joint is called the Schottky contact.

Awards

In 1936, Schottky was awarded with the Hughes Medal from the Royal Society for being able to discover the Schrot effect in the thermionic emission. The award was also given for inventing the screen-grid tetrode and the method for wireless signal reception through a superheterodyne.

He also received the Werner von Siemens Ring in 1964 because of the many different physical manifestations that his work gave basis to, especially for appliances which had to use semiconductors and tube amplifiers.

Because of his contributions, the Walter Schottky Institute in Germany was named after him, and so is the Walter H. Schottky prize. He was able to publish two books namely Thermodynamik in 1929, and Physik der Glühelektroden, Akademische Verlagsgesellschaft in 1928. He died in Pretzfeld, Germany on the fourth of March in 1976.