Advanced Materials Characterization Chapter 14 Atomic Force Microscopy

Advanced Materials Characterization Chapter 14 - by Igor Bello

Since the invention of scanning tunneling microscopy (STM) several new exciting surface analyses based on scanning probe techniques have been developed. The most notable is the atomic force microscopy (AFM) where the force between a stylus sharp tip and sample is used similarly as the tunneling current in STM. The spatial resolution of AFM is almost in the range of that of STM. More importantly, stylus tips and samples are not required to be electrically conductive.

In contact AFM mode, also known as repulsive mode, an AFM tip makes soft “physical contact” with the sample. The tip is attached to the end of a cantilever with a low spring constant, lower than the effective spring constant holding the atoms of sample together. As the scanner gently traces the tip across the sample (or the sample under tip), the contact force causes the cantilever to bend to accommodate changes in topography.