Very sharp platinum tips for scanning tunneling microscopy

Abstract

To achieve both high stability for scanning tunneling microscopy (STM) measurements and well-defined tunnel current localization even on very rough surfaces, we have developed a new electrochemical procedure using CaCl2 etching and H2SO4 micro polishing technique to obtain a very reproducible tip geometry. The mean curvature radius is about 50 Å. The contamination-free platinum tips are usable for a long time as well in air as in ultrahigh vacuum. The tip quality has been tested by STM measurements on gold (111) surfaces and on liquid-crystal films. Tips are stable and provide good STM image in far less time than commonly used tips.