Bipolar Junction Transistor
It works almost similar to a
simple
transistor. BJT is used for
amplifying and switching purposes. It is a 3 terminal device
(Base, Emitter, Collector) made of doped semiconductor
material like silicon. The working of BJT includes both the
electrons and holes. The electrons in base are called minority
carriers plays a vital role in BJT for current flow) because
the base is doped p-type which would make holes the majority
carrier associated with only small part of current to flow) in
the base.
BJT involves bi carrier types in charge flow
that is both electrons and holes unlike the FET (Field
effect Transistor) which has only one carrier type. It is of
two types NPN AND PNP Transistors.
A BJT consists of three doped semiconductor
regions, base region, the emitter region and the collector
region as below.
These regions are respectively p type, n
type and p type in a PNP, and n type, p type and
n type in a NPN transistor as shown in the figures.
Each semiconductor region is connected to a
terminal, labeled: emitter E, base B and collector C
