What is the PN junction diode?
A p-n junction diode is a basic semiconductor device that controls the flow of electric current in a circuit. It has a positive (p) side and a negative (n) side. If you’re reading this lesson on a computer or laptop that is plugged into an electrical outlet, then you’re probably making use of such a diode right now.
What is abrupt pn junction?
An abrupt junction is by definition a junction in which the doping type changes over a very small distance compared to the spatial extent of the depletion region (see below.) Figure EC1 : Donor and acceptor density profiles in an abrupt PN junction.
What is pn junction Class 12?
Definition: A P-N junction is an interface or a boundary between two semiconductor material types, namely the p-type and the n-type, inside a semiconductor.
How do pn junctions work?
When a p-n junction is formed, some of the free electrons in the n-region diffuse across the junction and combine with holes to form negative ions. In so doing they leave behind positive ions at the donor impurity sites.
What is the function of pn junction?
A p-n junction represents an electrical component with the function to allow an electric current in one direction (called the forward biased condition) and to block the current in the opposite direction (the reverse biased condition): a diode.
What is abrupt diode?
Abrupt varactor diodes As the abruptness of the junction is governed by the doping concentration and also the profile, this is controlled during the manufacture. For an abrupt varactor diode the doping concentration is held constant, i.e constant doping level as far as reasonably possible.
What is abrupt silicon?
An abrupt silicon p-n junction consists of a p-type region containing 1016 cm-3 acceptors and an n-type region containing also 1016 cm-3 acceptors in addition to 1017 cm-3 donors. Calculate the thermal equilibrium density of electrons and holes in the p-type region as well as both densities in the n-type region.
What is drift 12 semiconductor?
Due to the electric field developed at the junction, the electrons from the p-region move to the n-region. Similarly, the hole from the n-region move to the p-region. This results in drift current. The motion of charge carriers across the junction due to the electric field is called drift. This results in drift current.
Why depletion region is formed?
The depletion region is caused by the diffusion of charges. Because of the concentration gradient holes diffuse from p-side to the n-side across the junction while electrons diffuse from the n-side to the p-side. The holes and the electrons diffusing towards each other combine near the junction.
Why it is called depletion region?
The depletion region is so named because it is formed from a conducting region by removal of all free charge carriers, leaving none to carry a current.
What is the importance of pn junction?
The PN junction has the very useful property that electrons are only able to flow in one direction. As current consists of a flow of electrons, this means that current is allowed to flow only in one direction across the structure, but it is stopped from flowing in the other direction across the junction.
What is forward and reverse bias?
A forward bias has a substantial forward current, while a reverse bias has a minimal forward current. The depletion layer of a diode is substantially thinner while in forward bias and much thicker when in reverse bias. Forward bias decreases a diode’s resistance, and reverse bias increases a diode’s resistance.
What is forward bias?
Forward bias or biasing is where the external voltage is delivered across the P-N junction diode. In a forward bias setup, the P-side of the diode is attached to the positive terminal and N-side is fixed to the negative side of the battery. Here, the applied voltage is opposite to the junction barrier potential.
What is depletion region?
The word depletion in English refers to the decrease in the quantity of something. Similarly, in semiconductors, the depletion region is the layer where the flow of charges decreases. This region acts as the barrier that opposes the flow of electrons from the n-side to the p-side of the semiconductor diode.
What is step junction?
In a step graded PN junction diode, the concentration of dopants both, in the N side and the P side are uniform up to the junction. But in a linearly graded junction, the doping concentration varies almost linearly with the distance from the junction.
What is drift current in pn junction 12?
Drift current is the current flow in the diode due to the applied electric field.
What is depletion layer Class 12?
Depletion region or depletion layer is a region in a P-N junction diode where no mobile charge carriers are present. Depletion layer acts like a barrier that opposes the flow of electrons from n-side and holes from p-side.