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The presence of mobile and bound charges on either sides of the pn junction causes the depletion layer.
A pn junction is formed when a semiconductor is dopped with a pentavalent impurity on one side and a tri-valent impurity on the other side.on one side electrons will be more in number and on the other side holes will be more in number.At the junction the electrons combine with holes and there will be no charge carriers(i.e. electrons and holes) in that region.That region which is free from charge carriers is called depletion region.
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What is deplition region in a semiconductor?
Depletion region: Consider a diode .It is a basic semiconductor.It has two regions .A cathode (Negative-N) and anode(Positiv-P) regions.The N and P when connected together forms a diode.A junction will be created at the intersection of N and p regions .N region has electrons(-ve charge) and P region has holes(+ve charge) .At the junction the electrons from N region and holes from P region will join together .Particular area at the junction will have no charged particles after that.This region is called depletion region. If we give a voltage of 0.7V ,the depletion region will decrease and there will be current flow in the device.That voltage is called thershold voltage.
What is space charge region in pn junction?
The depletion region is also called as the space charge region.A p-n junction diode is formed by placing p and n type semiconductor materials in intimate contact on an atomic scale. This may be achieved by diffusing acceptor impurities into an n type silicon crystal or by the opposite sequence.In an open circuit p-n junction diode, majority carriers from either side will diffuse across the junction to the opposite side where they are in minority. These diffusing carriers will leave behind a region of ionized atoms at the immediate vicinity of the metallurgical junction. This region of immobile ionized atoms is called the space charge region.
In pn junction the depletion region capacitance increase with reverse bias or decrease?
any capacitance is given by equation C = (epsilon * A/ d) where d is distance between two plates, thus as d reduces C increases. Now, in depletion region as we increase reverse bias, the depletion region width increases. Now consider depletion region as a parallel plate capacitor, with positive charges on n side and negative charges on p side. Thus, as reverse bias increases, d of junction capacitance increases thus capacitance reduces. On other hand, as reverse bias reduces, d of junction capacitance reduces, thus capacitance increases. -Amey Churi
Why base spreading resistance is not considered at low frequencies?
Base spreading resistance depends on doping of the p-n junction and also the width of depletion region of the p-n junction. Thats what i knw.
How do you barrier voltage is developed?
The integration of the electric field across the depletion region is what develops the barrier voltage.
What will happen to the depletion region when the P-N junction is supplied by forward bias?
depletion region will decrease.
Why depletion layer width at the collector junction are more than the depletion layer width at the emitter junction?
The depletion layer width at the collector junction is typically wider than that at the emitter junction due to the differences in doping concentrations. The collector region is generally lightly doped compared to the heavily doped emitter region, resulting in a larger electric field and a broader depletion region. Additionally, the collector junction must accommodate a higher reverse bias, which further expands the depletion region to maintain charge neutrality and facilitate efficient charge separation.
What is depletion region in PN junction?
when the p type semi conductor is connected to n type the electrons in n type migrates towards p type to fill the vacancy i.e holes in p type. As a result accepter ions are developed in n type and donor ions in p type which restrict further movement of electrons and holes . this layer of donor and accepter ions at the pn-junction is called depletion region. and across this region a potential is developed which is called barrier potential.
Why charge carriers are not present in depletion region of am pn junction?
depletion region is formed only after recombination of holes and electrons..so in depletion region there are only and only immoble positive and nagative ions...hence,there is no charge carrier..
Why do the electrons are not atracted by the holes when they move in a diode?
they ARE, but only in close proximity (at the junction). this is what creates the depletion region around the junction: electrons being attracted to holes and falling in. once the depletion region gets wide enough attraction stops.
What is the depletion layer in a semi conductor?
in correct sense it is not the layer but the region around the metallurgical junction which is depleted of charge carriers .in this region an internal electric field exist which counter balance the diffusion of electron and hole around the junction . basically the main reason for the formation of depletion region is the concentration gradient across metallurgical junction of p-n semiconductor.
What is the difference between junction capacitance and diffusion capacitance?
Junction capacitance occurs at the depletion region of a p-n junction diode and is associated with the charge storage due to the electric field created by the built-in potential; it varies with the applied voltage. In contrast, diffusion capacitance is related to the charge carriers' movement across the junction when the diode is forward-biased, and it reflects the transient response of the charge carriers as they diffuse into the depletion region. Essentially, junction capacitance is linked to the static electric field, while diffusion capacitance is dynamic, arising from the flow of charge carriers.
What is NP junction capacitance?
NP junction capacitance refers to the capacitance associated with the depletion region of a p-n junction diode when a voltage is applied across it. This capacitance varies with the applied bias voltage, as the width of the depletion region changes, affecting the charge storage capability. It plays a crucial role in the frequency response and dynamic behavior of semiconductor devices, especially in applications like radio frequency and high-speed electronics. The capacitance can be modeled using the junction's built-in potential and doping concentrations.
Why zener diodes are heavily doped?
Zener diodes are heavily doped to create a narrow depletion region, allowing them to operate in the reverse breakdown region where they exhibit the Zener effect. This effect causes the diode to conduct in reverse bias at a specific voltage, ideal for voltage regulation applications.
How depletion region is narrowed during forward biasing?
When the pn junction is forward biased, some of the space charge is neutralized reducing the width of the pn junction.
What is depletion region in a diode?
As we bring P type and N type semiconductors fused together, then rich holes in P type would get neutralized with some rich electrons in N type. Hence at the juntion region, there will not be charge carriers ie holes and electrons. So it is known as Depletion Region. Depletion means emptying something. In case of ordinary diode this depletion region would be wider where as in case of Zener Diode the depletion region would be narrower. This is because the semiconductors are heavily doped. Hence potential barrier would be easily built up even with a thin region where holes and electrons get combined for neutrelization.
What Depletion region will form?
A depletion region will form at the junction of a p-type and n-type semiconductor in a semiconductor diode. This region is depleted of charge carriers, creating an electric field that prevents further flow of current in the reverse bias direction.
