Why Collector Region Is Moderately Doped?

What kind of diode is formed by joining a doped semiconductor region with a metal?


What kind of diode is formed by joining a doped semiconductor region with a metal?…Exercise :: Special-Purpose Diodes – General Questions.A.zenerD.step-recovery2 more rows.

Why collector region is large in transistor?

The collector region is the largest of all regions because it must dissipate more heat than the emitter or base regions. It is designed to be large because in order to dissipate all the heater, the extra surface area allows it to do so. … The larger area ensures that it has more surface area to dissipate heat.

Why emitter is forward biased?

Emitter is always forward biased w.r.t base so as to supply majority charge carriers to the base.

Why NPN transistor is preferred over PNP?

The majority charge carriers in an NPN transistor are electrons and the majority carriers in a PNP transistor are holes. The electrons have better mobility than holes. Therefore, NPN transistors are preferred over PNP transistors.

Why are collectors reverse biased?

The collector is kept at a higher potential than base or emitter so that the collector can attract all the electrons from emitter in case of a npn transistor as an example. For this to happen the collector base junction is reverse biased.

What is base region?

The base region is the region where a sufficient input current triggers a much larger current from the emitter to the collector of the transistor.

Which biasing method is the best?

Out of all these configurations voltage divider bias is the best, as the stability of this circuit with respect to change in beta, change in saturation current, change in base emitter voltage is more as compared to other configurations.

Which region is heavily doped?

The middle region is called the base and the outer two regions are called emitter and the collector. The outer layers although they are of same type but their functions cannot be changed. They have different physical and electrical properties. In most transistors, emitter is heavily doped.

Why base current is weaker than collector current?

Answer: Base is much narrower and thinner than collectors,hence the majority of charge carriers are received by collector. Hence,collector current is greater than base current.

Which region is heavily doped in Zener diode?

Explanation: Zener diode is heavily doped than the normal p-n junction diode. Hence, it has very thin depletion region.

When a reverse bias is applied to a diode it will?

5.1. Reverse bias usually refers to how a diode is used in a circuit. If a diode is reverse biased, the voltage at the cathode is higher than that at the anode. Therefore, no current will flow until the electric field is so high that the diode breaks down.

Which region is most heavily doped in a semiconductor transistor?

The emitter is heavily doped, so that it can inject a large number of charge carriers (electrons or holes) into the base. The base is lightly doped and very thin, it passes most of the emitter injected charge carriers to the collector.

Why emitter is forward biased and collector is reverse biased?

As shown in the above figure, the emitter to base junction is forward biased and the collector to base junction is reverse biased. Forward bias on the emitter to base junction causes the electrons to flow from N type emitter towards the bias. This condition formulates the emitter current (IE).

Which one is lightly doped?

In most transistors, emitter is heavily doped. Its job is to emit or inject electrons into the base. These bases are lightly doped and very thin, it passes most of the emitter-injected electrons on to the collector. The collector is so named because it collects electrons from base.

Which is the least doped region in a transistor?

The base region is less doped as a result of those maximum current streams from the emitter to the collector, through the base. Less doping in base region lets less recombination of charges while moving from emitter to the base, therefore maximum charge carriers move towards the collector allowing Ic to be maximum.

Which is faster NPN or PNP?

A NPN transistor has electrons as majority charge carriers whereas the PNP transistor has holes as majority charge carrier. The mobility of electrons is better than mobility of holes. … mobility of electrons is more than hole,so as a result npn transistor are faster than pnp that’s why they are preferred..

Can I use PNP instead of NPN?

Generally, the PNP transistor can replace NPN transistors in most electronic circuits, the only difference is the polarities of the voltages, and the directions of the current flow. PNP transistors can also be used as switching devices and an example of a PNP transistor switch is shown below.

Why is the base lightly doped?

The base region in a transistor is doped lightly so that the number density of majority carriers (electrons in p-n and holes in n-p-n transistor) is low. When emitter is forward biased, the majority carriers move from emitter to collector through base.

What is forward bias?

Forward biasing means putting a voltage across a diode that allows current to flow easily, while reverse biasing means putting a voltage across a diode in the opposite direction.

Is photodiode heavily doped?

The p-type and n-type semiconductors are heavily doped. Therefore, the p region and n region of the PIN photodiode has large number of charge carriers to carry electric current. … Therefore, majority carriers will not carry electric current under reverse bias condition.

Which transistor is mostly used?

NPN transistorGenerally the NPN transistor is the most used type of bipolar transistors because the mobility of electrons is higher than the mobility of holes. The NPN transistor has three terminals – emitter, base and collector. The NPN transistor is mostly used for amplifying and switching the signals.