was found to be light-sensitive, with a sharp boundary between p-type impurity at one end and n-type at the other. A slice cut from the specimen at the p–n boundary developed a voltage when exposed to light. The first working transistor was a point-contact transistor invented by John Bardeen, Walter Houser Brattain, and William Shockley at Bell Labs in 1947. Shockley had earlier theorized a field-effect amplifier made from germanium and silicon, but he failed to build such a working device, before eventually using germanium to invent the point-contact transistor. In France, during the war, Herbert Mataré had observed amplification between adjacent point contacts on a germanium base. After the war, Mataré's group announced their "Transistron" amplifier only shortly after Bell Labs announced the "transistor". In 1954, physical chemist Morris Tanenbaum fabricated the first silicon junction transistor at Bell Labs. However, early junction transistors were relatively bulky devices that were difficult to manufacture on a mass-production basis, which limited them to a number of specialised applications. See also Deathnium Semiconductor device fabrication Semiconductor industry Semiconductor characterization techniques Transistor count References Further reading G. B. Abdullayev, T. D. Dzhafarov, S. Torstveit (Translator), Atomic Diffusion in Semiconductor Structures, Gordon & Breach Science Pub., 1987 External links Feynman's lecture on Semiconductors How Semiconductors Work, HowStuffWorks Semiconductor Concepts at Hyperphysics Calculator for the intrinsic carrier concentration in silicon US Navy Electrical Engineering Training Series NSM-Archive Physical Properties of Semiconductors] Semiconductor Manufacturer List ABACUS: Introduction to Semiconductor Devices – by Gerhard Klimeck and Dragica Vasileska, online learning resource with simulation tools on nanoHUB Organic Semiconductors page DoITPoMS Teaching and Learning Package- "Introduction to Semiconductors" The Virtual Museum of Semiconductors Organizations Semiconductors