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p–n junctions represent the simplest case of a semiconductor electronic device; a p-n junction by itself, when connected on both sides to a circuit, is a diode. More complex circuit components can be created by further combinations of p-type and n-type semiconductors; for example, the bipolar junction transistor (BJT) is a semiconductor in ...
This effectively increases the potential barrier and greatly increases the electrical resistance against the flow of charge carriers. For this reason there will be no (or minimal) electric current across the junction. At the middle of the junction of the p–n material, a depletion region is created to stand
From Top to Bottom; Top: hole and electron concentrations through the junction; Second: charge densities; Third: electric field; Bottom: electric potential Figure 3. A PN junction in forward bias mode, the depletion width decreases. Both p and n junctions are doped at a 1e15/cm3 doping level, leading to built-in potential of ~0.59V.
[For a p-type Schottky barrier, Φ B is the difference between E F and the valence band edge E V.] A Schottky barrier, named after Walter H. Schottky, is a potential energy barrier for electrons formed at a metal–semiconductor junction. Schottky barriers have rectifying characteristics, suitable for use as a diode.
At the junction of two different types of the same semiconductor (e.g., p-n junction) the bands vary continuously since the dopants are sparsely distributed and only perturb the system. At the junction of two different semiconductors there is a sharp shift in band energies from one material to the other; the band alignment at the junction (e.g ...
The rectifying metal–semiconductor junction forms a Schottky barrier, making a device known as a Schottky diode, while the non-rectifying junction is called an ohmic contact. [1] (In contrast, a rectifying semiconductor–semiconductor junction, the most common semiconductor device today, is known as a p–n junction.)
When the transistor is in its so called 'off state' there is no voltage applied on the gate and the first p-n junction is reversed bias. The potential barrier is too high for the electrons to pass thus no current flows. When a voltage is applied on the gate the potential gap shrinks due to the applied bias band bending that occurs.
The result is a region at the interface, the p-n junction, where charge carriers are depleted on each side of the interface. In silicon, this transfer of electrons produces a potential barrier of about 0.6 V to 0.7 V. [6]