Drift current :

• It is due to the motion of charge carriers because of the force exerted on them by an electric field. It is the electric current, or movement of charge carriers which is due to the applied electric field or electromotive force over a given distance.

Diffusion current :

• It is a current in a semiconductor caused by the diffusion of charge carriers holes and/or electrons.

Mobility of Charge Carrier.

• This is a property of a conductor, defined as the ratio of drift velocity to applied electric field in a conductor.