Question

Pure silicon at zero K is:
1. An intrinsic semiconductor
2. An extrinsic semiconductor
3. A metal
4. An insulator

Answer 1

Correct Answer - Option 4 : An insulator

Concept:

• A pure semiconductor at 0 Kevin behaves as an insulator
• When the temperature is raised above absolute zero more electrons are detached from the covalent bond
• Thus, the electron-hole pairs are increased, when the temperature is raised
• These free electrons and holes move in a random manner
• When the electric field is applied across the semiconductor bar, it forces the randomly moving electron-hole pairs in its direction (field direction)
• This causes a current flow in the circuit which is called drift current
• In pure silicon, a major part of the drift current is due to free electrons because the mobility of electrons is greater than the mobility of holes