Scanning Tunneling Microscopy Profiling of Steep Ridges Using Metal-Coated Carbon Nanotube Tip

Abstract

We demonstrated the accurate imaging of steep ridges by scanning tunneling microscopy (STM) with a carbon nanotube (CNT) tip coated with a PtIr thin layer. Compared with the conventional tungsten tip, the PtIr-coated CNT tip could trace the shape of steep ridges (140 nm in width, 50 nm in height) more precisely with reduced artifacts originating from the finite shape of the tips. We also estimated the tip radius from the line profiles in the STM image, and proved that the tunneling current exactly flowed through the apex of the PtIr-coated CNT without bending or tilting of the tip during STM.