What is Atomic Force (Scanning Probe) Microscopy?
Better known as "atomic force" microscopy, SPM/AFM|
has grown in popularity and complexity over the last 5 years.
- Very high magnification to sub Angstrom range.
- Three-dimensional imaging - no sample preparation
if features are fine enough.
- Image in air, gas atmosphere, vacuum or under liquids.
- Supplementary measurements of physical properties
can be added. Examples - nano indent hardness and thermal
conductivity, all related to surface features.
- Scanning mechanism is the most important feature -
sample or probe can be moved.
- Made of a piezoelectric ceramic (PZT=lead zirconate
titanate) changes shape with applied voltage.
- Probe shape is important; depends on application
- mounted on cantilever arm 100 to 200 microns long.
- Tip radii are in the nano meter range.
- Some SPM systems are made as attachments to other visible
light microscopes (inverted stage type requuired).
One device by Omicron Assoc, Bethel Park, PA, operates from
25k to 900k in AFM mode or to 1,500k in STM mode.
- Sample Size - Burleigh Instruments, Fishers, NY
can go to 15 cm square x 2.5 cm high
- Possibly cost, but they are less expensive than even
the cheapest SEMS. $25k to $50k, compared to over $130k
- Apparently no simultaneous topography/chemical
composition information as with SEM/EDAX.