Atomic force microscopy – AFM

The atomic force and scanning tunnel microscope (AFM/STM) is especially well suited for very high resolutions. A surface is sampled with an ultra-fine tip, generating 3D images of the surface. Lateral resolutions of 1–10 mm and vertical resolutions of less than 1 nm are achieved. Monolayer steps can be resolved.  AFM is especially well suited for the characterization of extremely smooth surfaces. Material contrasts can be represented using friction force microscopy or modulation techniques. Roughness, steps or grain sizes can be measured with AFM as well as more complex parameters such as skewness, kurtosis, power spectral density and so on. Samples up to 10 cm in diameter with a thickness up to 3 cm can be examined with the equipment at Fraunhofer IST.

STM image of a metal DLC layer

Nanocrystal platinum particles in an amorphous carbon matrix.
© Fraunhofer IST

The illustration shows nanocrystal platinum particles in an amorphous carbon matrix. The platinum particles have a diameter of a few nanometres, but appear enlarged in the illustration due to folding with the geometry of the scanning tip.

Polymer surface

AFM tapping mode image of a polymer surface.
© Fraunhofer IST

AFM tapping mode image of a polymer surface. Tapping mode is an especially non-invasive sampling method. Even on soft materials such as polymers, it can be used for imaging without causing damage.

AFM of oxidic layers

Illustration of the nanocrystallites of a think titanium oxide film on glass.
© Fraunhofer IST

Illustration of the nanocrystallites of a think titanium oxide film on glass.