Semiconductor Materials
Semiconductor materials are nominally small band gap insulators. The defining property of a semiconductor material is that it can be doped with impurities that alter its electronic properties in a controllable way.

PN Junction Diode
A p–n junction is formed at the boundary between a p-type and n-type semiconductor created in a single crystal of semiconductor by doping.

Applications Of PN Junction Diodes
P-N junction diodes are widely used in almost all electronic circuits. Solar Cells,Rectifiers,Invertors have pn junction diodes as the basic component.

A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit.