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Atomic Force Microscopy (AFM)

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Technique

Since its invention in 1986 the Atomic Force Microscope (AFM) has been established as a standard tool for the imaging of sample surfaces down to the atomic scale. Last AFM generation includes particular probes in order to measure properties of the material like the magnetic, the electrostatic characteristics and the thermal conductivity.

 

The AFM principle is based on a tip (some nanometer apex size) that slide on the surface of the sample. The interaction forces between the tip and atoms of the sample surface (approximately nano-newton) cause a deflection of the lever on which the tip is mounted. Following a change of topography, a change in the deflection of the lever happens. A laser that hits the back side of the cantilever, is reflected towards a couple of photodiodes that adjust a ceramic piezoelectric scanner re-positioning the probe in the initial position. The recorded data is the voltage required to return the tip to the initial position. Scanning the sample surface, a three-dimensional image can be obtained.

Most important features

The great advantage of the AFM technique is that analyses are performed in air and, unlike STM, it allows microscopy on insulator materials. Besides it is a non-destructive analysis and it does not demand particular preparations of the samples.

Applications

It is particularly indicated for analysis of wafers, magnetic supports and compact discs, but you can perform satisfactory nanometer resolution images also on biological materials.

Instruments at ITC-irst

Solver P47H and Solver Pro SPM

Measuring modes

 

In air: contact AFM/ LFM/   ResonantMode (semicontact + noncontact AFM)/ Phase Imaging/ Force Modulation   (viscoelasticity)/ MFM/ EFM/ Adhesion Force Imaging/AFM Lithography-Force

In liquid: contact AFM/LFM/Adhesion Force Imaging/Force   Modulation (viscoelasticity) /ResonantMode(semicontact AFM)/Phase Imaging/AFM   lithography (Force) –petri dish usable-

Scanning heads

(dimensionX dimensionY dimensionZ)

high resolution: 10x10x2mm  (vertical resolution <0.5Å)

electrical measurements: 90x90x5mm (vertical   resolution <0.5Å)

liquid measurements: 90x90x5mm (+ double   z range)

scanner for heating stage: 50x50x2.5mm (until 300°C)

Max.sample diameter

15mm or not   restricted as stand alone

equipped   with heating stage and controlled gas environment