Table of Contents
Why collector width is high?
In most transistors, the collector region is made physically larger than the emitter region because it has to dissipate much greater power.
Why collector region is having more width than other two regions in BJT?
The width of the region depends upon their doping. The base region is lightly doped so that width of the base is less. Collector region of a transistor is highly doped so collector region has more width than other two.
Why Collector is moderately doped and large in size?
Base is lightly doped because we want that the base current should be small. Now the collector is moderately doped may be because we dont want a crowd of electrons in the collector otherwise the electrons coming from the Emitter-Base path may repelled and collector current may decrease.
Why collector is larger and base is smaller in BJT?
The reason the collector is the largest region is because it is the region which receives the majority of the current carriers, which for a npn transistor are electrons and for pnp transistors are holes. If the collector were smaller, it would overheat quicker, and, thus, the transistor would overheat easily.
Why BJT base is thin in size?
The base region in a transistor is made very thin so that there is a better conduction of majority carriers from emitter to collector through base. 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.
Why collector width is made larger than emitter and base width is smaller than other regions?
Collector is made physically larger than emitter and base because collector is to dissipate much power.
Why is emitter heavily doped in BJT?
The reason the emitter is the most heavily doped region is because it serves to inject a large amount of charge carriers into the base, which then travels into the collector, so that switching or amplification can occur. In npn transistors, the n-type emitter injects free electrons into the base.
Why are the emitter base and collector of a BJT doped differently?
To improve the emitter efficiency and the common-base current gain (a), it can be shown that the emitter should be much heavily doped than the base. A low doping level of the collector increases the size of the depletion region. This increases the maximum collector-base voltage and reduces the base width.
Why the base current in a transistor is small compared to the emitter and collector current?
In a BJT, the base current is small because the base region is small and the reverse biased collector junction voltage draws most of what are now minority carriers into the collector before they can exit the base.
Why is the collector made larger than the emitter and the base also why is emitter the most heavily doped?
In most transistors, emitter is heavily doped. Its job is to emit or inject electrons into the base. The collector is so named because it collects electrons from base. The collector is the largest of the three regions; it must dissipate more heat than the emitter or base.