Direct and Indirect band gap semiconductors
Direct Band gap semiconductors 1. In energy versus momentum diagram maximum of valency band occurs at the same value of momentum as the minimum of conduction band.
2. The direction of motion of an electron during transition across energy gap remains unchanged.
3. Life time of charge carriers is less.
4. It is observed in compound semiconductors like Gallium Arsenide (GaAs), Indium Phosphate (InP), Cadmium Sulphide (CdS)
5. It is used in Light emitting diodes (LED's) and Laser diodes.
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Indirect Band gap semiconductors1. The maximum of valance band does not occur at the minimum of conduction band.
2. The direction of motion of electron during transition across energy gap alters.
3. Life time of charge carriers is high.
4. It is observed in pure semiconductors like Silicon, Germanium.
5. It is used in amplifying the signals.
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