Electrically conducting AFM probes can be used to chemically modify a surface
to "draw" an image. For example, applying an electrical bias between the
conducting probe and a substrate can locally oxidize selected regions of
the surface to form patterns.
The dimensions of the pattern drawn by electrically conducting techniques
depends on:
- Diameter of the probe
- Potential between probe and surface
For growing an oxide on silicon, the line-width of the pattern ranges up
to tens of nanometers. The thickness can be controlled in the range of
10-50 nm. When the writing is done in ambient air, the line width depends
on the relative humidity, because water adsorbed at the tip-substrate
interface focuses the electric field and also acts as the anodization medium. The oxide thickness was found to depend on the electric field strength. Figure 3 shows two patterns written in silicon oxide with an AFM.
