3. Size measurement by atomic force microscopy (AFM)

3.1 Principle of AFM measurement

Atomic force microscopy is used, among other things, to visualize the topography of a sample. A flexible micrometer lever with a tip at its free end, the apex of which can be likened to a sphere a few tens of nanometers in diameter, is used to scan the surface of a sample. When the tip is brought close to the surface, forces, which may be attractive or repulsive, arise, causing the lever to deflect. In order to convert the deflection of the lever into an electrical signal, a detection system is used at the AFM head. Several techniques can be used (interferometric, piezoelectric, capacitive, piezoresistive). However, it is the optical deflection detection method that is most commonly implemented, for which a focused laser beam is reflected off the back...