SURFACE-POTENTIALS ON PD GAAS CONTACTS STUDIED USING SCANNING PROBE MICROSCOPY/

Two Pd/GaAs contacts annealed at different temperatures were evaluated with the current-voltage measurement to be Schottky and ohmic contact s, respectively. Using a scanning probe microscope that is capable of surface potential measurement, we measured the contact potential diffe rences (CPDs) for the Pd/GaAs Schottky contact and confirmed that ther e is no significant potential barrier for the Pd/GaAs ohmic contact in terface. By defining the ohmic electrode on the rear side of the GaAs substrate to be the reference electrode, we observed that the surface potential on the GaAs surface is almost constant and attributed this t entatively to be a result of the CPD between the probe tip and GaAs su rface.