1. The space between the tip and the surface atoms represents the potential barrier.
2. Apply a potential between the tip and the surface.
3. Electron (wave property) obeys quantum rules and therefore can tunnel through the surface giving rise to tunnelling current.
4. The tunnelling current depends on the barrier gap.
5. Keep current constant by adjusting the gap as the tip moves across surface atoms.
6. By measuring the height of the gap as the tip moves over the entire surface , we can obtain the surface topography.
Summarize from pg 68
