Starting in 1931, Welker studied at the
University of Munich under
Arnold Sommerfeld, and was granted a Ph.D. in 1936. The book
Electrodynamics - Lectures on Theoretical Physics Volume III by Sommerfeld was based on lecture notes prepared by Welker during the winter semester of 1933/1934. Welker was granted his
Habilitation under Sommerfeld in 1939. During the
war years, 1940 to 1945, Welker worked at Luftfunkforschungs Institut in
Oberpfaffenhofen, but still maintained association (1942 to 1944) with the physicochemical institute of
Klaus Clusius at the University of Munich. After the war, 1947 – 1951, he took a job at the
Westinghouse subsidiary in
Paris,
Compagnie des Freins et Signaux Westinghouse. From 1951 to 1961, Welker headed of the solid-state physics department of
Siemens-Schuckertwerke, in
Erlangen, where he developed the new,
III-V compounds such as
gallium arsenide and
indium antimonide, to replace silicon
semiconductors. His work resulted in large-scale use of galvanomagnetic and
optoelectronic effects, as well as new switching circuits in
microelectronics. Welker and his department paved the way for
microwave semiconductors and
laser diodes. He was the director of the Erlangen Siemens-Schuckertwerke research laboratory from 1961 to 1969. From 1969, until he retired in 1977, Welker was director of all the company's research laboratories. While at the Westinghouse subsidiary in Paris, Welker and German physicist
Herbert F. Mataré developed a point contact semiconductor amplifier, demonstrated in June 1948. This coincided with the announcement by
Bell laboratory scientists of the demonstration of a point contact transistor on 30 June 1948. The French Westinghouse subsidiary applied for a patent on the same type of device on 13 August 1948. On 18 May 1949, this European invention coined as the "Le Transistron" or the "French transistor" was presented to the public, while a first batch of 1,000 devices was manufactured for the French telecommunications. This development was an outgrowth of work done by the two independently in Germany in programs to develop German
radar. The French patent was granted in 1952. Welker was elected president of the
Deutsche Physikalische Gesellschaft in 1977. ==Selected Literature==