SURFACE-POTENTIAL EFFECTS IN THE ELECTROOPTIC PROBING OF THE HALL-EFFECT IN BULK GAAS

The Hall effect in bulk Si-doped GaAs (n = 3.4 X 10(-18) cm-3) has bee n observed using an electro-optic voltage probing (EOVP) technique, wh ich is noninvasive and eliminates the necessity for metallic voltage p robes. Essentially the Hall voltage is measured by detecting the induc ed birefringence created by this transverse voltage. The change in pol arization of the probing beam is plotted as a function of the magnetic field which induces the Hall field. A transverse voltage is observed, without the application of a magnetic field. This 'background' voltag e is investigated, and we believe it is due to the surface potential d ifferences between the upper and lower surfaces.