This article presents an implementation of high-resolution imaging in Kelvin force microscopy (KFM) using the multi-frequency approach in the intermittent contact mode. The basic function of atomic force microscopy – high resolution imaging of surface topography is usually performed in the resonant oscillatory modes: amplitude modulation or frequency modulation. When a conducting probe is applied in the AFM-related electric modes it senses also the electrostatic tip-sample forces. Simultaneous and separate detection of the mechanical and electrostatic forces can be realized by using the probe response at different resonant and non-resonant frequencies. In KFM, a nullification of the electrostatic force is applied for detection of a local surface potential. The described experimental set-up and procedures help us to reveal the surface potential variations with high sensitivity and spatial resolution. The examples of KFM studies of metals, semiconductors and molecular systems with dipole moments demonstrate how this technique can be applied for advanced and quantitative characterization of heterogeneous systems.
Nanogaps by direct lithography for high-resolution imaging and electronic characterization of nanostructures
