Local probing of thermal properties at submicron depths with megahertz photothermal vibrations

We demonstrate the imaging of buried features in a microstructure—a tiny hole in an aluminum thin film covered by a chromium layer—with nanometer lateral resolution using a transient temperature distribution restricted to within ;0.5 mm of the sample surface. This is achieved by mapping photothermally induced megahertz surface vibrations in an atomic force microscope. Local thermal probing with megahertz-frequency thermal waves is thus shown to be a viable method for imaging subsurface thermal features at submicron depths. © 2003 American Institute of Physics. @DOI: 10.1063/1.1539906#