History of Computers - Semiconductors
Semiconductors are an integral part of today's electronics. Without them, computers would still be operated by vacuum tubes.
Contents
Overview
Semiconductors are found in the 4th family of the periodic table, the elements which have 4 electrons in their outer shell. Their outer electrons allow for a very uniform crystalline structure, demonstrated in carbon as diamond. The very stable balanced structure causes these crystal structures to be insulators, as there are no free electrons to allow for a current. For a semiconductor to become conductive, the material must be injected with slight impurities, or "doped."[1] The impurities cause either "holes" where there is a lack of electrons in P-type doping, or adds in extra electrons in N-type doping, the two forms caused by different counts of valence electrons. In a diode the two types of doped silicon are pressed together, which causes a current to be able to pass in one direction. In transistors, there is a sandwich of either PNP or NPN silicon, where a current cannot flow in either direction unless a smaller current is running through the center pin.[1] For more info on why the diodes and transistors behave in this way, click here.
