The first is to remove them mechanically by dragging the tip across the substrate surface.
We now consider the case of an overlaying superstructure on a substrate surface.
The nearer the layers are to the substrate surface, the more energy is needed to remove them.
Pyrolysis leaves the atoms on the substrate surface in the second step.
The atoms bond to the substrate surface and a new crystalline layer is grown in the last step.
Formation of this epitaxial layer occurs at the substrate surface.
Condensation of these molecules on the substrate surface results in thin film formation.
Bombardment prior to deposition is used to sputter clean the substrate surface.
This way, the contamination of the gas phase and damage of the substrate surface can be reduced.
The vertical nano structures are also created directly on the substrate surface.