Pure semiconductors (such as Silicon and Germanium) have a moderate number of charge carriers (electrons and holes) that allow them to conduct electricity under certain conditions.

They also have a small energy gap (bandgap) between the valence band (full of electrons) and the conduction band (where electrons can move freely).

Doping:

Doping introduces impurities into the semiconductor to increase its conductivity.

Types:

• N-Type: Adding donor atoms (like phosphorus) with extra electrons increases the number of free electrons (negative charge carriers).
• P-Type: Adding acceptor atoms (like boron) creates holes (positive charge carriers) by accepting electrons from the valence band.

How They Work

• Electrons: In n-type semiconductors, free electrons are the majority carriers. They move from the negative side (cathode) to the positive side (anode).
• Holes: In p-type semiconductors, holes (the absence of electrons) are the majority carriers. They act as positive charge carriers, effectively moving from the positive side to the negative side.

Applications

• Diodes
• Transistors
• Integrated Circuits (ICs)