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September 9, 1912 – physicist Heinrich Welker is born.
Heinrich Welker, 1970
Heinrich Welker was born on September 9, 1912, in Ingolstadt. Upon completion of his secondary school education, Welker moved to Munich to study mathematics and physics. From 1935 to 1940 he worked as a scientific assistant to Arnold Sommerfeld at the Institute for Theoretical Physics. He received his doctorate in 1936 with a dissertation on wave mechanics. His interests during this period were focused on superconductivity, a specialization that would earn him a lecturing position at the University of Munich three years later.
Following his employment at the Wireless-Telegraphic and Atmospheric-Electrical Testing Station in Gräfelfing and its successor, the Air-Ground Communication Research Institute in Oberpfaffenhofen, he worked as a scientist at the Physical-Chemical Institute of the University of Munich: It was here in 1942 that he succeeded in demonstrating the semiconducting properties of germanium and developed a rectifier design for high-frequency electromagnetic waves. Following this patent, Siemens produced some 10,000 crystal diodes from purest germanium by 1945. Welker also developed an initial theory of what was later called the field-effect transistor with capacitive control of electricity in a three-electrode semiconductor design.
After a brief intermezzo running his own engineering firm in Planegg outside Munich, Welker decided to go abroad. In 1947 he accepted the position of laboratory director at the French headquarters of Westinghouse in Paris. But he returned to Germany only four years later. In 1951, as director of the department of solid-state physics for Siemens Research in Erlangen, he discovered the III/V compounds consisting of elements of the third and fifth groups of the periodic table. This discovery led to broad application of galvanomagnetic and optoelectric effects and to completely new switching elements in microelectronics – including gallium arsenide, which to this day is still important for high-frequency components and laser diodes in optoelectronics.
After the complete Siemens-Schuckertwerke research laboratory in Erlangen was acquired, Welker and the research group he built became a pioneer of microwave semiconductor elements as well as LEDs and laser diodes based on compound semiconductors. When Siemens AG was founded, the research labs in Munich and Erlangen were merged in 1969 under Welker’s management. From 1973 to 1977, Welker was the head of Corporate Research and Development. After his retirement, the 65-year-old remained president of the German Physics Society for one more year.
Heinrich Welker died on December 25, 1981, in Erlangen. Alongside the many distinctions he received during his lifetime, Siemens AG honored him posthumously in 1982 by endowing the Heinrich Welker Medal, a gold medal awarded in collaboration with the GaAs Symposium Award of the International Symposium on Gallium Arsenide and Related Compounds.
10. September 2012 – Dr. Franz Hebestreit