Karl Baedeker (scientist)

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Karl Baedeker (ca. 1877 – 1914) was a German physicist, and a professor at the University of Jena. He was the grandson of  Karl Baedeker, the founder of the eponymous travel guide publishing house, and the son of Fritz Baedeker (1844 - 1925), who ran the same company from 1869 until his death in 1925 (see Baedeker).

One of his scientific discoveries was that the resistivity of cuprous iodide (CuI) depended on its stoichiometry. Thin films of the material became much more conductive when exposed to iodine vapor; the effect was reversible. This was the first example of doping a semiconductor to change its properties. He also observed a Hall effect in copper iodide that had the reverse sign to that in metals, an observation of what was later to be known as conduction by electron holes in semiconductors. This observation was critical in developing the theory of electron conduction in solids. Along with his graduate student Karl Steinberg, Baedeker studied the effect of varying concentration of iodine on the electrical properties of copper iodide.

Baedeker was killed in action in August 1914 during World War I at the Battle of Liège. His son, Karl Friedrich Baedeker revived the Baedeker publishing house after the Second World War.