Bridge-enhanced nanoscale impedance microscopy

A conductive atomic force microscopy (cAFM) technique has been developed that is capable of quantitatively measuring the magnitude and phase of alternating current flow through the tip/sample junction with a five order of magnitude improvement in sensitivity. Bridge-enhanced nanoscale impedance microscopy (BE-NIM) uses a tunable resistor/capacitor bridge circuit to null the spurious contribution to the tip/sample current caused by fringe capacitance between the cAFM cantilever and the sample. As a proof of principle, BE-NIM is used to characterize an array of electron-beam lithographically patterned metal-oxide-semiconductor capacitors and compared directly to conventional nanoscale impedance microscopy. In addition, BE-NIM is applied to a multiwalled carbon nanotube/poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene) nanocomposite material, on which the alternating current behavior of individual nanoscale conductive pathways is quantitatively probed.