3 ω -scanning thermal microscope

Abstract

We present the theoretical and experimental calibrations of a scanning thermal microscope (SThM) based on a hot anemometer wire probe. Under ac heating and due to the linear dependence of the probe electrical resistance to temperature, the third harmonic of the tip voltage is also linear to the temperature. This method called “3-ω” is currently used to estimate the thermal properties with a hot strip deposited on the sample surface. However, in this last technique, the sensor size allows one to reach the sample transient thermal behavior whereas the SThM tip does not. We propose a thermal model showing what information can in fact be obtained by using the microscope under the 3ω mode. We finally report an experimental calibration providing the tip/sample contact thermal parameters.