Scanning Probe Microscopy

Scanning probe microscopy (SPM) is a technique to examine materials with a solid probe scanning the surfaces. SPM started with the scanning tunneling microscope (STM). An STM uses a tunneling current, a phenomenon of quantum mechanics, to examine material surfaces. The tunneling current flows through an atomic-scale gap between a sharp metallic tip and conducting surface atoms. The SPM added a popular member, the scanning force microscope (SFM). An SFM is commonly called an atomic force microscope (AFM). It uses near-field forces between atoms of the probe tip apex and the surface to generate signals of surface topography. The AFM is more widely used than the STM because it is not restricted to electrically conducting surfaces. While SPM offers unique advantages for surface measurement in terms of simplicity and high resolution, it also has its unique problems of image artifacts caused by near-field interactions between tip and sample.