|Cantilevers for AFM work are nanofabricated from silicon.
The cantilevers shown at right are still attached to the original chip.
These cantilevers are fabricated with pyramidal tips of silicon nitride.
Pyramidal tips made from silicon nitride are the most durable variety. They have a low aspect ratio (sharpness) and are suitable for low-profile subjects. They are most often used for friction force microscopy because of their durability.
The silicon nitride tip shown below has
a chip near the vertex and is not perfectly curved. Each tip must be
regarded as an invdividual. For the most critical work, the shape of the tip
must be verified.
High aspect-ratio tips are commonly made from silicon and carbon. These tips are more useful in vibrating (tapping mode), which greatly reduces lateral forces that would otherwise damage the tip. Bryan Todd and Stephen J. Eppell, Case Western Reserve University have compiled data on tip sharpness using tip deconvolutiontechniques.
|SEM image of a conical etched silicon probe for TappingMode™ from Digital Instruments.||SEM image of a NanoTOOLS high-density carbon modification (HDC) tip.|
Revised: November 11, 2003
Copyright © John W. Cross