Veeco Dimension 3100, Manual

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Contact AFM
Advanced Atomic Force Operation
126 Dimension 3100 Manual Rev. D
thickness of both cantilevers are equal. The calculated spring-constant for each of the cantilever
configurations is listed below in
Table 8.2a . These values are approximations and significant
variability occurs. The tabulated values are used to approximate contact force unless more accurate
values are measured by the user.
Table 8.2a Cantilever Spring Constants
The 100µm wide-legged cantilever are used on most samples. If the image degrades rapidly
because the tip damages the sample surface, switch to a cantilever with a lower spring-constant.
Cantilevers with smaller spring-constants are used on softer samples which are destroyed by
imaging with high-contact forces.
Etched Silicon Tips
Etched silicon tips have a higher aspect ratio and smaller end radius than the silicon nitride
cantilevers. Because they are sharper, etched silicon tips provide better resolution and have less
applied capillary forces. Most samples in air are covered by a thin layer of water and other
condensed contaminants. These contaminants often form a capillary bridge between the tip and
sample, generating large adhesive forces, also referred to as capillary forces (see
Figure 8.2a ). For
more force curve information, see Chapter 13 .
Figure 8.2a Force Curve
Cantilever Type
k (N/m)
Narrow Legs
k (N/m)
Wide Legs
100µm
(triangular)
0.38 0.58
200µm
(triangular)
0.06 0.12
A
B
C
D
E
Approach
Jump to contact
Contact
Adhesion
Pull-off