Surface potential mapping: A qualitative material contrast in SPM

Electric potential measurements on different metals and semiconductors have been performed using a scanning probe microscope. The measured potential shows a clear chemical contrast in all cases, allowing us to differentiate between different materials down to 100 nm in size with potential noise smaller than 1 mV. The lateral potential resolution as a function of the tip-sample distance has been measured and numerical calculations of the force density acting on the tip are presented along with theoretical examinations of the quantitative potential resolution.