Overview of Scanning Probe Microscopy Techniques

Scanning Probe Microscopy has enabled researchers to image surfaces at the nanometer scale. Rather than using a beam of light or electrons, SPM uses a fine probe that is scanned over a surface (or the surface is scanned under the probe). By using such a probe, researchers are no longer restrained by the wavelength of light or electrons. The resolution obtainable with this technique can resolve atoms, and true 3-D maps of surfaces are possible. Scanning Probe Microscopy is a general term, used to describe a growing number of techniques that use a sharp probe to scan over a surface and measure some property of that surface. Some examples are STM (scanning tunneling microscopy), AFM (atomic force microscopy), and NSOM (Near-Field Scanning Optical Microscopy).

Basic idea of scanned probe techniques:

The number of techniques is constantly growing, as the tip can be modified in many ways to investigate surface properties. In addition, the use of a tunneling current, simple force feedback or light through an aperture in the probe enable different ways to interact with the surface.

The following sections review Scanning Tunneling Microscopy, Atomic Force Microscopy & its multiple variations, and NSOM (or SNOM).