Question

In p type semiconductor hole moves in:
1. Conduction band
2. valance band
3. both conduction and valance band
4. Forbidden region

Answer 1

Correct Answer - Option 2 : valance band

Ans: Option: 2

CONCEPT:

• P-type semiconductor: When trivalent impurity like boron, aluminum, etc. is added to a pure semiconductor the resulting crystal is called P-type or positive type semiconductor.

EXPLANATION:

• A large number of holes or vacant space in the covalent bond is created in the crystal with the addition of the trivalent impurity. A small or minute quantity of free electrons is also available in the conduction band. Since the holes are more in number as compared to the electrons in the conduction band.

• Holes initially remains in the valence band.

• When the electric field is applied across the doped semiconductor crystal, an electron from neighboring covalent jumps into the hole but creates a hole in the original bond. This process is repeated and thus the hole appears to move through the crystal in the direction of the field.

• Valance band: The range of energies possessed by valance electrons is known as the valence band.
• Conduction band: The range of energies possessed by conduction electron is known as the conduction band.
• Forbidden energy gap: The separation between the conduction band valance band on the energy level is known as the forbidden gap.