Question
A semiconductor is a material with a small but non-zero band gap that behaves as an insulator at absolute zero but allows thermal excitation of electrons into its ____________ at temperatures that are below its melting point.
✓
Answer
- Conduction band
The band gap in case of semiconductors is of order 3−4 eV. At absolute zero, the valence band is filled and conduction band is empty, so it behaves as an insulator. As the temperature is raised, electrons in the valence band gain sufficient energy to overcome the band gap and jump to the conduction band.
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