Tip-sample capacitance as a function of the spacing. As the tip oscillates above the sample surface, the tip impedance is also modulated at the same frequency. The inset shows the schematic of the tapping mode AFM and the microwave electronics (D—directional coupler, A—amplifier, M—mixer), as well as the cantilever structure and the SEM of the Pt tip. The scale bar is 500 nm.
First harmonic MIM-C signal on several thin-film and samples. The FEA simulation results are also plotted for comparison. The inset shows the quasistatic potential distribution for a certain configuration—tip diameter , tip-sample separation , film thickness .
(a) Layer structure of the sample. (b) AFM image of the polished sample surface. (c) Contact and (d) tapping mode MIM-C images taken by the same tip at the same area. The darker regions are buried . Electronic drift can be observed in (c) but not in (d). Line cuts are shown in both (c) and (d) for comparisons of the signal strength and the spatial resolution.
(a) SEM picture of nanoribbons and In/Au electrodes. The tapping data on the same devices are shown as (b) topography, (c) MIM-C, and (d) MIM-R images. The lower left device is more conductive than the one in the upper right.
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