Explanation

The charge carriers in metals are electrons, while in semiconductors they are electrons and holes. mobility refers to the average drift velocity of charge carriers (electrons and holes) under the action of a unit electric field, which is a measure of the speed at which charge carriers move under the action of an electric field. Carriers generated for some reason are in irregular thermal motion. When an external voltage is applied, the carriers inside the conductor are subjected to electric field forces and undergo directional motion to form a current, known as drift current. The drift velocity direction of positively charged carriers is the current direction, while negatively charged carriers are the opposite. The speed of directional movement is the drift speed, and the direction is determined by the carrier type. Under the electric field, the average drift speed p of the carrier is proportional to the electric field intensity E, and the coefficient is the drift mobility of the carrier. The mobility of current carrier is an important parameter reflecting the conductivity in semiconductors. The mobility is not only related to the strength of the conductivity. And it directly determines the speed of carrier motion. During its thermal motion, charge carriers constantly collide with lattice, impurities, defects, etc., irregularly changing their direction of motion. Scattering occurs. Drift velocity is actually a statistical average controlled by scattering events.

Classification