Thermal expansion and temperature measurement in a microscopic scale by using the Atomic Force Microscope

An experimental study on microscopic scale measurements of thermal expansio n and temperature by using the Scanning Joule Expansion Microscope (SJEM) b ased on the Atomic Force Microscope (AFM) was conducted.. While the AFM is scanning on the sample heated by AC current, topographical and thermal expa nsion images are measured simultaneously by detecting DC and AC motions of the cantilever. In order to apply this technique to the temperature measure ment in microscopic scale, the sample was covered with a thin film of polym er (PMMA) which has a high thermal expansion coefficient compared with meta ls and dielectric materials. Merits of this technique are (1) quite simplic ity of measurement because of using the commercial cantilever instead of co mplicated thermal cantilever for the typical Scanning Thermal Microscopy (S ThM) and (2) a higher spatial resolution of 20 nm which is restricted by th e point contact scale between the cantilever and the sample.