Measurement Services

Null Point Scanning Thermal Microscopy (NP SThM)
Quantitative 1-D profiling of the temperature and spreading thermal resistance:
The principle of NP SThM

NP SThM is based on the thermodynamic principle that the heat flux through the tip–sample contact becomes zero when the temperatures of the probe tip and sample surface are the same. Hence, NP SThM measures the temperature that is not perturbed by the heat flux through the tip–sample thermal contact. Furthermore, NP SThM can be used to obtain a quantitative profile of the temperature distribution of the sample surface, even when the tip–sample contact resistance is unknown or changes during a scan owing to changes in the surface properties. Therefore, NP SThM can solve all three problems of conventional SThM: (i) distortion of the measured signal due to heat transfer through air, (ii) the unknown and variable value of the tip–sample thermal contact resistance, and (iii) perturbation of the sample temperature due to the heat flux through the tip–sample thermal contact.

This feature greatly expands the applicability of NP SThM as a thermal characterization technique. However, in order to obtain a high spatial resolution, which is the primary motivation for SThM, NP SThM requires an extremely sensitive SThM probe such as NP SThM01 that can trace the vanishingly small heat flux through the tip–sample nanothermal contact.

Through NP SThM, by utilizing the exceptional performance of NP SThM01, we provide quantitative 1-D profiles of the temperature and local spreading thermal resistance with nanoscale resolution independent of the changing tip–sample thermal contact resistance and without perturbation of the sample temperature or distortion due to the heat transfer through air.