AFM is a method for the measurement of surface topography, and other related properties of solid surfaces, with atomic resolution normal to the surface. The AFM Laboratory is equipped with XE-70 AFM of Park Scientific Corp. (Korea). The instrument operates in all major AFM modes (contact, non-contact, tapping mode, lateral force microscopy, etc.). While the vertical resolution of the instrument approaches the size of a single atom, the lateral resolution is mainly determined by the parameters of the tip employed in the measurements. Resolutions of 5 to 10 nm can be routinely achieved with commercially available tips.
The advantage of the XE-70 instrument is the de-coupling of scanning in X-Y direction from the vertical scanning (Z-direction), realized through the two separate piezoelectric scanners. This eliminates the cross-talk of X-Y and Z scanning directions (intrinsic in the case of tube scanners), and significantly extends the maximum range of heights (about 12µm) accessible by the instrument. The instrument is equipped with the piezoelectric X-Y scanner with the maximal scanning range 40 x 40 µm2.
The applications of AFM include (but are not limited to) the measurements of surface topography of thin polycrystalline films (for determining grain size and morphology), semiconductor devices, tribological surfaces, hard and soft coatings, polymers after various surface treatments, etc. For example, a surface map of the friction coefficient can be acquired in the lateral force microscopy mode. Qualitative mapping of the elastic properties of a surface can be achieved by acquisition of the phase signal in non-contact mode.
The AFM has a number of advantages over the scanning electron microscope (SEM):
- relative ease of operation, no vacuum is needed (i.e. wet or biological samples can be studied);
- better resolution in Z-direction;
- both conducting and non-conducting samples can be investigated.
However, acquiring a high-quality AFM image requires more time than in SEM (typically, 20 – 30 min), and direct analysis of the chemical composition of the surface is impossible.
For more information, please contact Michael Kalina at 04-8295795.