What is Transistor?

 

Transistor is symmetrical to a vacuum triode and relatively very small in size. Transistor is a composition of two words Transfer and Varistor. A transistor consists of three layers of semi conductor material and each layer is having the capability of transferring current to the other layers. This three layer semiconductor device consisting of either two n-type and one p-type layers of material or two p-type and one n-type layers of material. First type is called an npn transistor, while the other is called a pnp transistor respectively.

Germanium and silicon are most preferable semiconductor materials which conducts electricity in semi energetic way. By the process of doping to the semi conductor material, the result adds additional electrons to the material or produce holes in the material. The outer layers have widths much greater than the inserted p-type or n-type material that is typically in 10:1 ratio or less. Lower doping level decreases the conductivity and increases the resistance of this material, by limiting the number of free carriers.

The difference between the diode and the transistor is: A diode is made up of two layers and one junction. Transistor is made of three layers with two junctions. A transistor can acts as an on/off switch or an amplifier.