IMPROVED KELVIN METHOD FOR MEASURING CONTACT POTENTIAL DIFFERENCES BETWEEN STEPPED GOLD SURFACES IN ULTRAHIGH-VACUUM

A new mechanical system and a convenient piezoelectric driven Kelvin p robe for the measurement of the contact potential difference (CPD) und er ultrahigh vacuum are described. Charging effects on CPD measures ar e discussed. The probe is small (2.2 mm diam) and allows cartography o f the surface. The mechanical system is frictionless so the distance b etween the sample and the probe can be maintained constant and at a lo w value (approximate to 20 mu m). By elimination of charging effects, reliable and reproducible results can be obtained within +/-10 mV. The system is tested on gold vicinal surfaces. (C) 1995 American Institut e of Physics.