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A p–n junction is a boundary or interface between two types of semiconductor material, p-type and n-type, inside a single crystal of semiconductor. It is created by doping, for example by ion implantation, diffusion of dopants, or by epitaxy (growing a layer of crystal doped with one type of dopant on top of a layer of crystal doped with another type of dopant). If two separate pieces of material were used, this would introduce a grain boundary between the semiconductors that would severely inhibit its utility by scattering the electrons and holes. p–n junctions are elementary "building blocks" of most semiconductor electronic devices such as diodes, transistors, solar cells, LEDs, and integrated circuits; they are the active sites where the electronic action of the device takes place. For example, a common type of transistor, the bipolar junction transistor, consists of two p–n junctions in series, in the form n–p–n or p–n–p. The discovery of the p–n junction is usually attributed to American physicist Russell Ohl of Bell Laboratories. However, Vadim Lashkaryov reported discovery of ''p''-''n''-junctions in CuO and silver sulphide photocells and selenium rectifiers in 1941. A Schottky junction is a special case of a p–n junction, where metal serves the role of the p-type semiconductor. == Properties == The p–n junction possesses some interesting properties that have useful applications in modern electronics. A p-doped semiconductor is relatively conductive. The same is true of an n-doped semiconductor, but the junction between them can become depleted of charge carriers, and hence non-conductive, depending on the relative voltages of the two semiconductor regions. By manipulating this non-conductive layer, p–n junctions are commonly used as diodes: circuit elements that allow a flow of electricity in one direction but not in the other (opposite) direction. ''Bias'' is the application of a voltage across a p–n junction; ''forward bias'' is in the direction of easy current flow, and ''reverse bias'' is in the direction of little or no current flow. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「P–n junction」の詳細全文を読む スポンサード リンク
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