STM probe tip formation by ion bombardment of rough W-surface

The morphological evolution of cone development on a tungsten surface during Ar ion bombardment as high as 1 keV has been studied. The presence of irregularities or asperities on the bombarded surface has been found to be more effective in initiating cone formation than varying the dose or energy of the Ar ions. Emery paper has been used to polish the tungsten surface, and cone development during ion bombardment has been observed. These cones can be used as probe tips for a scanning tunneling microscope (STM). We can easily produce the STM probe with a tip curvature radius of about 1.5 nm, a conical angle of 20, and a height of 13 nm. This probe can achieve greater than 0.5 nm STM image resolution.