Fabrication of Nanogap Electrodes Using Ultrathin Metal Film

We fabricated a trench structure on an ultrathin, flat Pt film by a scratching technique using an atomic force microscope (AFM) tip. Precise control of the loading force of the tip during the scratching process made it possible to fabricate a fine trench structure without Pt debris on both sides of the trench. Nanogap electrodes were made by this method. Their electrical isolation was confirmed by Kelvin-probe force microscopy (KFM) measurements. Furthermore, we evaporated methylquinquethiophen (M5T) molecules onto the nanogap electrodes and measured the current-to-voltage (I-V) characteristics of the M5T film. We demonstrated that electrical measurements by KFM, utilizing ultrathin Pt nanogap electrodes, was a very attractive method of investigating the local properties of organic molecular films.