AFM for Nano-Surface Texture/Roughness

There are two primary potential sources of error in using an AFM for measuring surface textures. The first is the probe geometry and the second is the length scale of the measurement.

Probe Geometry:
The surface texture that is measured with an AFM depends on the geometry of the probe tip. If the probe tip is larger than the features causing the surface texture, then the surface roughness measurements will appear smaller than they should be. This possible source of error is avoided by using the sharpest possible probe.

Length Scale:
Within the image used for the surface/area roughness calculation there must be an adequate sampling of the features giving rise to the surface texture. As a result, it is possible to get a different surface texture when the scan size is changed. This problem is avoided by using the same size scan range when surface roughness on several samples is being compared.