Solid materials having properties in between conductors and insulators are known as semiconductors. A semiconductor is a material that is neither a good conductor nor a good insulator of electricity. Its resistivity lies in between conductors and insulators, which is 100 Ω cm. The energy gap between conduction and valence band is narrow for semiconductors with respect to insulators.
With the rise in temperature, the electrons in the valence band gain energy and jump to the conduction band. Because the forbidden energy gap is very narrow, this means that such materials due to small changes in potential difference or temperature are changed from insulators to conductors. Because of this fact, the resistivity of semiconductors decreases with temperature.
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