Quantitative dynamic near-field microscopy of thermal conductivity

A new three-dimensional finite element method model of the conventional resistive thermal probe, usually employed within scanning thermal microscopy (SThM) has been developed. As a result, the line heat source characteristic of the bent thermal sensitive filament seems to permit the explanation of the experimental results within a certain frequency range. The verification of this line heat source characteristic of the thermal probe finally leads to the introduction of a general near-field condition of SThM, which considers the spatial and temporal characteristic of the heat source. Here, the contact area between the probe and the sample is not considered as the source but rather as the aperture between the heat source and the sample. In addition, the combination of this kind of thermal probe with the so-called 3omega-method has been justified for the quantitative determination of the local thermal conductivity. Moreover, the applicable sample thermal conductivity range has been expanded significantly by considering the varying heat flow into the sample within the conditional equation.