Just as water undergoes autoionization into H+ and OH- , Si-Si bonds in Si can undergo the loss of an electron to produce a mobile hole (a one-electron bond between Si atoms) and a mobile electron.Just as there is an ion product constant for water, Kw, there is an equilibrium constant for the concentration of holes and electrons, p and n, in a semiconductor such as silicon.At the right is a plot of the hole concentration versus 1/T for various semiconductors; and of the proton concentration versus 1/T for water.p-type refers to semiconductors with p > n.n-type refers to semiconductors with n > p.These are endothermic reactions, illustrating Le Chatelier's principle that products are favored by an increase in temperature.
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