Functional Probes for Scanning Probe Microscopy

For superior performance of scanning probe microscopy, we are working to fabricate functional probes. For Kelvin probe force microscopy, we fabricated a metal-tip cantilever by attaching a thin metal wire to a regular Si cantilever and milling it by focused ion beam (FIB)$^{1}$. By using the W tip with a curvature radius of 3.5 nm, we obtained the potential profile of Ge/Si(105) surface in atomic resolution with the energy resolution better than 3 meV$^{2}$. For synchrotron-radiation-light-irradiated scanning tunneling microscopy which aims at atomically resolved elemental analysis, we fabricated a glass-coated W tip using FIB$^{3}$. It is found that the glass coating blocks the unwanted secondary electrons, which come from large area of the sample, by a factor of 40 with respect to the case no coating. Using the tip to detect the electrons emitted just below the tip, we obtained element specific images with a spatial resolution better than 20 nm under the photo irradiation whose energy is just above the adsorption edge of the element$^{4}$. 1 K. Akiyama \textit{et al.}, RSI \textbf{76}, 033705 (2005) 2 T. Eguchi, K. Akiyama \textit{et al.}, PRL \textbf{93}, 266102 (2004) 3 K. Akiyama \textit{et al.}, RSI \textbf{76}, 083711 (2005) 4 T. Eguchi, K. Akiyama\textit{ et al.}, APL, in press