Transparent and conductive Sb-doped tin oxide SPM tips prepared by sol–gel method

The rapid progress in scanning probe microscopy (SPM) techniques in the last decade has induced an increasing need for manufacturing advanced SPM tips. One important case is conductive and transparent tips. For such tips, only a few techniques have been proposed, which are either expensive or have poor reproducibility. We here propose a simple and cheap sol–gel technique to prepare fibers with a suitably sharp apex so that they can be used as SPM tips. The fibers were spinned off from a high-viscosity solution of tin alkoxide and SbCl3 hydrolysed in humid air and baked at 520 °C for several hours. The radii of the resulting tips were estimated by transmission electron microscopy to be less than 50 nm. The resistivity of the transparent fibers was measured using different Sb-doping (0.5–1 wt.%) of the tin oxide. The temperature dependence of the conductivity and light absorption were investigated down to liquid He temperatures.