SOLUTION

When an external electric field is applied to an intrinsic semiconductor more number of electron holes pair combinations will be broken.

• Under the influence of the external electric field, an equilibrium condition is disturbed and electrons move in a direction opposite to that of holes. Holes can be thought of as positively charged particles.
• The movement of electrons in the conduction band and that of holes in the valance band constitutes the current in a semiconductor.
• Electrons and holes together are known as Charge carders.
• Thus in a semiconductor, the current is constituted by two types of carriers: (a) electrons and (b) holes. In metals, conduction is due to electrons only.