PN junction

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pn junction

[¦pē¦en ‚jəŋk·shən]
The interface between two regions in a semiconductor crystal which have been treated so that one is a p-type semiconductor and the other is an n-type semiconductor; it contains a permanent dipole charge layer.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

PN junction

The interface at which p-type silicon and n-type silicon make contact with each other. At this coupling point, free electrons (n-type) and holes (p-type) cancel each other and form a "depletion zone" that acts as a non-conductive barrier. The PN junction is one of the primary building blocks of semiconductors.

Diodes and Thyristors
A diode (one way valve) is a PN junction with p-type on one side and n-type on the other. When a positive voltage is applied to the p-type side (forward bias), it shrinks and overcomes the depletion zone, causing the current to flow from the p-type to the n-type side. When a negative voltage is applied to the p-type of the diode (reverse bias), it increases the depletion zone and prevents current from flowing. See diode.

Built like two diodes in a row (three PN junctions) but with a third terminal, a thyristor is a one-way valve that, once turned on, lets current flow until it falls below a certain threshold (see thyristor).

Bipolar Transistors
Double PN junctions are used to build bipolar transistors. These p-type/n-type bipolar "sandwiches" are called "PNP" and "NPN" transistors. See bipolar transistor and n-type silicon.

PN Junctions
Placing p-type silicon next to n-type silicon is the primary way many semiconductor devices are constructed. The field effect transistors (FETs) in CMOS chips also use n-type and p-type silicon, but are designed differently (see FET and MOSFET).
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References in periodicals archive ?
Once the minority carrier charge is removed, the PN junction moves to its nonconductive state (e.g.
PN junction varactors are based on the variation of the PN depletion capacitance when the reverse bias voltage is varied.12 Figure 1 shows PN junction varactor with an N-well zone with P+ and N+ contact islands The PN junction produces the capacitance variation with reverse bias voltage.
As [V.sub.oc] is related to the overall minority carrier recombination inside the solar cells, a higher [V.sub.oc] indicates that the cell with NDL has a better surface passivation effect while still maintaining the same pn junction quality.
From the discussion mentioned above, one can interpret this photo-response polarity changing TPV by employing a combined theoretical model of pn junction and Schottky potential.
Approximately 10 years ago, a detailed evaluation of minority-carrier lifetimes of a variety of pn junction diodes was performed.
The varactor model is well established as the series combination of a small resistor and a nonlinear capacitor representing the voltage charge relation in a reverse-biased PN junction diode.