ac thermal imaging of nanoheaters using a scanning fluorescent probe

Using a fluorescent particle glued at the end of a sharp tip, we observe the heating of a 200 nm wide nickel nanoheater run by an alternating electrical current. The images clearly show the heating of the nickel structure, as well as the lateral heat diffusion in the dielectric layers underneath. By monitoring the fluorescence changes as the tip approaches the nanoheater, we have estimated the relative importance of the different heat transfer mechanisms between the device and the fluorescent particle. It is shown that, for the investigated structures, heat transfer occurs mainly by direct contact between the probe and the surface. (c) 2008 American Institute of Physics.