Answer to Question #110125 in Electric Circuits for hamid

Question

Why electron-hole pair is concerned only with semiconductors and not with metals(conductors)? As electron leaves atoms(positively charged) in both SC and metals.

Answer 1

In the metal, the band gap between the valance band conduction band is zero so free electron can eaisly jump from valance band to conduction band.But in the insulator there is high gap available between the valance band and the conduction band, electron can not jump easily from valance band to conduction band so it is insulator.

But in the semiconductor, have a gap between the valance band the conduction band is small, when the external energy such as heat or potential is given, then electron can easily jump from the valance band to conduction band. Hence there is a possibility to control the current flow in the semiconductor.