The semiconducting properties of lead chalcogenides (compounds of lead with sulfur, selenium, and tellurium) have been known for about one hundred years. In 1865, Stefan observed the thermoelectric power of natural PbS crystals (galenite) and reported different signs of the thermoelectric power for different samples. (We now know that these different signs indicate n- and p-type conduction.) Rectification at a contact between a metal and a semiconductor (PbS) was discovered by F. Braun in 1874 , and used in the early stages of the development of point-contact crystal detectors in radio engineering. The photovoltaic effect at a metal — semiconductor contact was also observed and exploited in lead chalcogenides.
KeywordsCarrier Density Thermoelectric Power Thermoelectric Generator Lead Sulfide Fundamental Absorption Edge
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