On the Hall Voltage in an Inhomogeneous Material

The Hall effect has been considered in an inhomogeneous material consisting of low-resistivity grains separated by thin layers of high resistivity. It has been shown, in contradiction to another recently presented model, that the Hall effect gives the carrier concentration of the low-resistivity grains and can consequently be used to distinguish between a ``numbers'' mechanism and a ``barrier'' mechanism for photoconductivity in a material.