NIST logo

Nathan Shemonski

University: Washington University in St. Louis
Major: Computer Science and Electrical Engineering
Graduation Date: 05/09
Hometown: Parkton, MD

Project: Scanning Kelvin Force Microscopy (SKFM) is an imaging technique which can be used to determine the work function of a sample. Simple methods of SKFM can be performed using the boxed equipment and software that are purchased with the AFM. It becomes more difficult, though, to perform more advanced scanning techniques such as Frequency Modulated SKFM (FM SKFM) due to a lack of access to internal signals.

Performing FM SKFM is very desirable for many reasons. First, it can give a quantitative value of the work function. Using the boxed equipment alone, one cannot reliably determine quantitative values for work functions without tedious calibration. With small changes in parameters, the measured work function can change drastically. Second, FM SKFM relies on the phase of the vibrating cantilever which is much more sensitive to forces and thus higher special resolution can be achieved. Finally, FM SKFM is performed using a single pass which can conceivably double the speed of imaging since two scans over the same line are required when using the boxed scanning techniques.

To implement FM SKFM, multiple external feedback loops were implemented. The main piece of these feedback loops is a cheap digital signal processor (DSP). Success in this project would be exciting since it would mean higher resolution images for a small amount of money.


Nathan Shemonski