FABRICATION AND CHARACTERIZATION OF TIPS FOR ELECTROCHEMICAL SCANNING-TUNNELING-MICROSCOPY

We report a new technique for preparing tips for electrochemical scanning tunneling microscopy (ECSTM) with particular consideration of its simplicity and reproducibility. In preparing scanning tunneling microscopy (STM) tips by electrochemical etching, we chose an etching process with the formation of a neck-shaped part of an etched wire by applying a suitable etching voltage, and then we adopted a two-step etching process to prevent over etching. The prepared tip possessed a curvature of 100 to 300 nm, much smaller than that of the tip prepared by the conventional method. The etched tip was insulated with silicon rubber or epoxy resin under an optical microscope. This controllable technique allows that a reproducible tip with an exposed area of 0.44 to 1.76 mu m(2), which has proved to be available for in situ experiment, could be made.