In a transistor, identify the terminal with the highest doping from the options given below.

Concept:

Transistor:

• A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit.
• Bipolar Junction Transistor is constructed with three doped Semiconductor Regions (Base, Collector, and Emitter) separated by two p-n Junctions.
• The emitter, Collector, and Base is the correct order of decreasing impurities.

Doping is the intentional introduction of impurities into an intrinsic semiconductor for the purpose of modulating its electrical, optical, and structural properties.

• The emitter is heavily doped. Its job is to emit or inject electrons into the base.
• Bases are lightly doped and very thin, it passes most of the emitter-injected electrons onto the collector.
• The doping level of the collector is intermediate between the heavy doping of the emitter and the light doping of the base.
• The doping level and width of the base are kept light so that most of the charge carriers are transferred from emitter to collector without much recombination. 
• So the doping concentration of the Emitter(E), Base (B), and Collector(C) region of a typical bipolar junction transistor varies as E > C > B.

Important Points 

Transistor has three regions:

Emitter:

• Highly doped
• medium area

Collector:

• Moderate doping
• largest area

Base:

• lightest doping
• lightest area

Explanation:

With reference to the collector, the Emitter is heavily doped.

So, the correct option is Emitter