Surface potential investigation of fullerene derivative film on platinum electrode under UV irradiation by Kelvin probe force microscopy using a piezoelectric cantilever

Abstract

Dynamic-mode atomic force microscopy (DFM) combined with Kelvin probe force microscopy (KFM) has been a powerful tool not only for imaging surface topography but also for investigating surface potential on a nanometer-scale resolution. We have developed DFM / KFM using a microfabricated cantilever with a lead zirconate titanate (PZT) piezoelectric thin film used as a deflection sensor. The observed sample can be in a completely dark environment because no optics are required for cantilever deflection sensing in our experimental setup, which is also equipped with a mechanism to irradiate ultraviolet (UV) light onto the sample. We prepared a platinum-on-silicon substrate and deposited fullerene-derivative (PCBM; [6,6]-Phenyl-C61-Butyric Acid Methyl Ester) film patterns by vacuum evaporation with two shadow masks in crossed directions. The energy band diagram with band-bending, it was created by simultaneously obtaining topographic and surface potential images of the same area using the developed DFM / KFM.