Physics 111 Advanced Laboratory. Professor Sumner Davis

This video accompanies the Hall Effect in a Semiconductor Experiment, providing students with an introduction to the theory, apparatus, and procedures.

The Hall effect is the phenomenon of a voltage developing across two boundaries in a direction transverse to the current flow in a system of charged particles in a magnetic field owing to the Lorentz force q(v x B).

Semiconductors fall in between two extremes, conductors and non-conductors, and their properties require some knowledge of condensed matter physics. The Hall Effect illustrates the Lorentz force v X B. For a doped germanium crystal, you measure the resistivity, concentration of the free carrier, and the Hall coefficient as functions of the temperature. When a current is passed through a sample in the x-direction, the Lorentz force acting on the electric charges moving in a magnetic field B ( in Z) displaces some carriers in the y-direction and causes an internal electric field EH which cancels the Lorentz force in the equilibrium case. You will use the Van der Pauw method of measuring a sample of arbitrary shape for a temperature range from 300K to 77K to 400K.
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