- The electrical conduction in a semiconductor is due to free electrons in the conduction band and holes [vacant sites] in the valence band.
- The free electron current is in the opposite direction to the conventional current. But the hole current is in the same direction of the conventional current.
- The movement of the free electron and holes are in the opposite direction in the presence of applied field .
- The total current in the semiconductor is the sum of the free electron current and hole current.
- The free electrons and holes are produced by thermal ionization of atoms by breaking the covalent bonds due to applied voltage.
- There are intrinsic and extrinsic semiconductors.
- Intrinsic semiconductors are pure form of semiconductors.
- Extrinsic semiconductors are impure form of semiconductors [doped semiconductors].
- By the process of doping, the impurities are added in the intrinsic semiconductors by which the holes and free electrons are produced.
- If pentavalent (Phosphorous, arsenic, antimony) impurities are doped, then the free electrons are produced, this semiconductor is called N-type semiconductor.
- If trivalent [Aluminium, Gallium,indium] impurities are doped, then the holes are produced, then this semiconductor is called P-type semiconductor.
Conduction in Semiconductors
For Feedback - techactive6@gmail.com