SURFACE INVESTIGATIONS WITH A KELVIN PROBE FORCE MICROSCOPE

The contact potential difference between a reference tip and sample can be measured with high spatial resolution using a modified version of the scanning force microscope. The instrument is comparable to a Kelvin probe but allows the simultaneous imaging of contact potential difference and, in addition, topography. The contact potential difference is not only dependent on the material, i.e. work function, but also on the condition of the surface. Therefore changes in contamination, stress, temperature, the crystalline structure, oxide-layer properties and (trapped) charges can significantly alter the contact potential difference. Initial results concerning these parameters will be presented.