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The Atomic Force Microscopy Resource Library


Scanning Probe Microscopy (SPM)

Scanning Probe Microscopy (SPM) is a large and growing collection of instrumentation methods for investigating the properties of a sample at or near the sample surface. The SPM instrument has a sharp probe (radius of curvature typically in the nanometers or 10‘s of nanometers) that is in near contact, or perpetual contact, or intermittent contact with the sample surface.

When we say an SPM is used to investigate sample properties at or near the sample surface, by near the surface, we mean immediately beneath the surface (typically several nanometers deep) and immediately above the surface (typically up to several tens of nanometers high). This is a limitation in the sense that the bulk of a thick specimen is generally inaccessible to SPM methods. Nonetheless, today there are tens and possibly over a hundred different SPM techniques, and the list of their applications in science and engineering is growing.

SPMs were first used to create 3-dimensional images of the sample surface, and even though that is still the main application, other techniques that do not always involve 3-dimensional images have ensued and the sphere of methodology and applications keeps expanding. In this tutorial, we will visit some of the techniques and their applications.

The small, finite size of the probe’s sharp end is one key element that gives the SPM its resolution power, but it is also a limitation of SPM. As the probe can only interact with a small area of the sample surface at any given time, it becomes necessary to raster-scan either the sample or the probe in the XY plane to cover an area and create an image of that area.

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