Our STM was tested for functionality, accuracy, and the repeatability of its measurements by scanning a 22K gold sample. The results proved that the STM is fully functional with a scan range of 6 Angstroms to 1.2 –microns in both the x and the y directions.

The accuracy of the measurements was verified by touching the surface with the tip, exerting pressure to dig a tiny hole on the gold sample, and then scanning this hole with the STM. Since the STM is immediately above the hole when lifted up slightly, it was possible to see the effects of pressure on the surface. The accuracy of the results was verified by comparing the width of the whole to the thickness of the IrPt tip. The STM was found to be accurate to a fraction of a nanometer.

Another way to verify the correctness of the STM’s operation was to check for the repeatability of results. It was seen that repeatedly scanning the same area gave similar results, and that averaging increased the repeatability. The STM gave stable results even when we waited for more than 10 minutes between the measurements.

As a result, we have reached all of the goals that we had initially set up for this project. We also succeeded in implementing additional features such as real-time imaging and constant-current mode operation that we initially saw as unrealistic. In the end, we were very pleased with the outcomes.

A typical good example of 200nm x 200nm gold surface,
topological and 3D surface view

The same surface as above, scanned a few minutes later

Another 200nmx200nm gold surface scanned consecutively with a slight shift to the right

The scanned area of the gold surface where the tip of the microscope has been pressed into. Note the hole produced by the tip.
The same surface, topological view
The same surface, 3-D view