Table of Contents
What are the doping levels of BJT?
A BJT consists of three differently doped semiconductor regions: the emitter region, the base region and the collector region. These regions are, respectively, p type, n type and p type in a PNP transistor, and n type, p type and n type in an NPN transistor.
Which layer of BJT is heavily doped?
emitter
In a BJT, emitter is heavily doped whereas base and collector are lightly doped.
What are the three regions of a transistor and their doping concentration?
(1) Base, emitter, and collector regions have similar size and doping concentrations. (2) The base region must be very thin and lightly doped. (3) The emitter-base junction is forward biased and the base-collector junction is reverse biased.
What is base width in BJT?
Modern BJTs have base widths of about 0.1 µm.
What layer of the transistor is the widest?
The collector is the largest region of a BJT transistor. 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.
Why is base width small 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.
What is metallurgical base width?
The metallurgical base width of a silicon npn bipolar transistor is xB0 = 0.80 μm. The base and collector doping concentrations are NB = 5 × 1016 cm−3 and NC = 2 × 1015 cm−3, respectively.
Which region of BJT has maximum width?
collector region
In a BJT, collector region width is maximum when it.
Which element has the biggest size in transistor?
The element that has the biggest size in a transistor is Collector.
- A transistor is made of three elements emitter, collector, base.
- Emitter works as a negative lead, collector works as a positive lead and base helps to activate the transistor.
Why is the base layer thin and lightly doped?
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. …
How many junctions are there in a BJT?
The transistor has two junctions. One between emitter and the base and other between the base and the collector. Because of this the transistor is similar to two diodes, one emitter diode and other collector base diode. In a BJT, why is the emitter heavily doped?
What is the doping level of collector in a transistor?
The doping level of collector is intermediate between the heavy doping of emitter and the light doping of 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. The transistor has two junctions.
How many layers does a BJT transistor have?
There are two types of BJT; n-p-n transistor and p-n-p transistor. Out of these two types, the n-p-n transistors widely use compare to the p-n-p transistor. It has four layers. The first layer is a heavily doped emitter layer (n+). The second layer is moderately doped the base layer (p).
What are the basic symbols of BJT?
The basic symbols of BJT are n-type and p-type. Electronic current is conducted by both free electrons and holes in bipolar junction transistor. There are three terminals in bipolar junction transistors are explained below. Emitter − It supplies charge carriers.