Scanning Kelvin microprobe in the tandem analysis of surface topography and chemistry

Abstract

This article presents the principles of operation, performance and applications of a scanning Kelvin microprobe for combined contact potential and surface topographical measurements. The new instrument uses a miniaturized vibrating probe for exploring, point by point, the surface of a sample, through measurement of the current emerging from the local ‘capacitor’ formed between the vibrating tip and the surface. In particular, the instrument is capable of simultaneously imaging the contact potential difference and topography of a scanned surface. This tandem characterization provides unique information regarding material properties. The lateral resolution is 1 µm, the topographic resolution is in the nanometer range and contact potential sensitivity is in the millivolt range. We also present preliminary studies of graphite, silicon, mica, metal and polymer surfaces.