The use of galvanomagnetic experiments to determine the mobility and density of carriers in the spacecharge region of a semiconductor surface is considered. In part I an approximate model is used: it is a single crystal composed of two regions, a surface region of thickness of the order of a Debye length and a bulk region. Expressions for the resultant Hall coefficient are given for three experimental configurations by use of circuit analysis. The sensitivity of each configuration is derived, and by also considering experimental desirability, one is selected for study. It has the magnetic field perpendicular to the surface and the Hall voltages of surface and bulk are in parallel. Changes in Hall voltages of 1 to 50% are expected by using ambients to change the surface potential.

In part II the model is assumed to be a single crystal with continuous variation of the potential in the direction perpendicular to the surface. Rigorous expressions are derived for the Hall coefficient and magneto-resistance by use of the one-dimensional Boltzmann equation. A feature of the derivation is its independence of a specific model of the surface region. The resulting expressions contain surface densities and mobilities which can be evaluated from experimental data of Hall coefficient and conductivity. Conversely, the expressions can be used with theory based on specific surface models to predict values of conductivity, Hall coefficient, and magnetoresistance.

• Received 20 January 1958

DOI:https://doi.org/10.1103/PhysRev.110.1254