  Hot tips are used either for characterizing nanostructures by using scanning
thermal microscopes or for local heating to assist data writing. The tip-sample
thermal interaction involves conduction at solid-solid contact as well as
conduction through the ambient gas and through the water meniscus. We analyze
those three heat transfer modes with experimental data and modeling. We
conclude that the three modes contribute in a similar manner to the thermal
contact conductance but they have distinct contact radii ranging from 30 nm to
1 micron. We also show that any scanning thermal microscope has a 1-3 microns
resolution when used in ambient air.
