Atomic force microscopy
Atomic force microscopy (AFM) is used to analyze the surface topography of smooth surfaces. AFM produces high-resolution images that can be used in roughness analysis. The technique has applications in multiple fields, including physics, molecular engineering, and medicine.
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What is AFM analysis used for?
Atomic force microscopy is commonly used for surface roughness measurement during the development of thin films, semiconductors, and coatings. Its vertical resolution can reach a sub-angstrom (0.1 nm) level, making AFM an excellent tool for analyzing tiny height differences on smooth, hard samples.
How does atomic force microscopy work?
During AFM analysis, a probe with a sharp tip is attached to a cantilever that scans over the sample surface. The tip is moved vertically by a feedback loop to keep a tip-sample interaction at a constant level. The surface topography of the sample is constructed by recording the vertical movements. The movement of the probe is typically recorded with a laser beam that is focused onto the end of the cantilever. The reflection from the laser is detected with a position-sensitive photodiode (PSPD).
Atomic force microscopy is based on forces that interact between the cantilever tip and the sample surface. A decrease in the distance between the tip and sample surface increases repulsive forces that formed due to the overlapping atomic orbitals. These interactions are used as an input for the feedback loop.
In contact mode, a probe tip is constantly in contact with the sample surface, and the vertical deflection of the cantilever is kept constant during the scan. AFM contact mode can produce high-resolution topography images.
AFM tapping mode can be used when the sample is too fragile for the contact mode. In tapping mode, the surface is scanned with an oscillating cantilever. The tip is positioned so that it intermittently contacts the surface of the sample. The tapping mode uses the amplitude of cantilever oscillation to detect changes in the tip-sample interaction forces. The probe is moved vertically with a constant amplitude. This lateral movement is recorded to form topographical information. PSPD is used to measure the movement of the cantilever oscillation.
Non-contact mode AFM is a non-invasive technique because the cantilever tip is not in direct contact with the sample. The cantilever oscillates near its resonant frequency close to the surface, and changes in the cantilever’s resonant frequency or vibration amplitude are detected.
Suitable sample matrices
- Thin films
Ideal uses of AFM
- Characterizing the topography of solid surfaces
- Obtaining 3D images on surface roughness and texture
- High-resolution imaging of surfaces
Frequently asked questions
AFM analysis is used to determine the topography of smooth surfaces like those of thin films and wafers. It can produce 3D images of surface profiles and surface roughness values.
AFM contact mode may harm some sample matrices because the tip is in direct contact with the sample.
AFM is suitable for a wide range of surfaces, including polymers, ceramics, composites, glass, and some biological samples.
Measurlabs offers a variety of laboratory analyses for product developers and quality managers. We perform some of the analyses in our own lab, but mostly we outsource them to carefully selected partner laboratories. This way we can send each sample to the lab that is best suited for the purpose, and offer high-quality analyses with more than a thousand different methods to our clients.
When you contact us through our contact form or by email, one of our specialists will take ownership of your case and answer your query. You get an offer with all the necessary details about the analysis, and can send your samples to the indicated address. We will then take care of sending your samples to the correct laboratories and write a clear report on the results for you.
Samples are usually delivered to our laboratory via courier. Contact us for further details before sending samples.