Phase imaging test specimen

Phase Imaging is a sharp probe, which is brought into proximity with the specimen surface. The probe is oscillated vertically near its mechanical resonance frequency. As the probe lightly taps the surface, the amplitude of oscillation is reduced and the AFM uses this change in amplitude in order to track the surface topography. In addition to its amplitude, the probe motion can be characterised by its phase relative to a driving oscillator. The phase signal changes when the probe encounters regions of different composition. 

Phase shifts are registered as bright and dark regions in phase images, comparable to the way height changes are indicated in height images. Phase images often show extraordinary contrast for many composite surfaces of technological and scientific interest. These include contamination deposits, discontinuous (i.e. defective) thin films, devices built of composite materials (e.g. magnetic recording heads), and cross-sectional specimens of composite materials. Both inorganic and organic materials can be examined. 

We have found that phase imaging is more convenient and gentler than other methods, which are based on contact mode operation. It routinely achieves lateral resolution of 10nm.