Scanning Tunneling Microscopy (STM) is a versatile imaging technique used in nanotechnology and materials science to obtain high-resolution, three-dimensional images of surfaces at the atomic scale. The technique relies on the principle of quantum tunneling, where a fine-tipped probe is scanned over a conductive sample surface, allowing the measurement of the electrical currents resulting from the tunneling of electrons through the vacuum gap between the tip and the surface.
STM works by maintaining an ultra-sharp conducting tip just a few atoms above the sample surface, and applying a tiny bias voltage between the tip and the surface. When the tip is brought closer to the surface, electrons can tunnel through the vacuum barrier, creating a measurable current. The feedback mechanism in STM maintains a constant tunneling current by adjusting the tip height, resulting in detailed measurements of the surface topography.
By scanning the tip laterally across the sample surface, STM can generate a detailed image of the surface structure with sub-nanometer resolution. Furthermore, STM is not limited to imaging conductive samples but can also probe their electronic and magnetic properties by measuring the energy and spin states of the electrons tunneling through the junction.
Thanks to its remarkable resolution and versatility, STM has greatly contributed to various fields such as materials science, nanotechnology, surface chemistry, and biological sciences. It has provided valuable insights into the atomic arrangement of materials, enabling the study of surface processes, defect structures, and the manipulation of atoms and molecules at the atomic scale.
