Figure 1.

Profiles of the etched and insulated gold probes. Optical images under 250× magnification of (a) a good etched gold STM probe which is smooth, straight, and sharp such that it reaches an apex of radius less than 1 μm, (b) a poor etched gold STM probe which is not smooth or sharp, such that the apex of this tip is visibly rounded, and (c) a good coated STM probe with a smooth and continuous coating which comes to a point at the apex, and has no visible protrusions there. An TEM image (d) of typical good STM probe with radius of curvature equal to 8.3 nm in this case.