question_answer

A pure semiconductor behaves, slightly as a conductor at:

A) high temperature           

B) room temperature

C) low temperature            

D) none of the above

Correct Answer: B

Solution :

Key Idea: At room temperature some valence electrons acquire   thermal energy to go to conduction band. A semiconductor is a material with an electrical conductivity that is intermediate between that of an insulator and a conductor. In a semiconductor at room temperature, some of the valence electrons acquire thermal energy greater than band gap energy \[{{E}_{g}}\] and cross over into the conduction band. These free electrons, and the (positive) holes created in the valence band, can move about even under a small applied field. The solid is therefore slightly conducting. The conductivity further increases with increasing temperature.