8.3 Electrical conductivity of a semiconductor

In a semiconductor, the conduction band electrons and valence band holes will participate in electrical conduction. To obtain an expression for electrical conductivity, we consider a rectangular bar of intrinsic semiconductor connected to a battery as shown in Fig. 8.3. Then, electric field exists along X-direction. This field accelerates the free (or conduction band) electrons along negative X-direction and holes along X- direction. So, the velocity of electrons along negative X-direction increases and attains some constant resultant velocity. This constant velocity is called drift velocity, represented as vd. This drift velocity is superimposed on their random thermal motion. The total electrical ...

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