The scanning tunneling microscope (STM) and atomic force microscope (AFM) are both powerful tools used to study the surface of materials. However, they operate in different ways and yield different results. In this blog post, we will take a closer look at the differences between these two microscopes.
What is AFM?
AFM is an Atomic Force Microscope. AFM is a versatile tool that can be used to measure a variety of properties at the nanoscale. AFM can be used to measure topography, surface roughness, and mechanical properties such as stiffness and adhesion. AFM can also be used to investigate electronic properties and to fabricate nano-scale devices. AFM operates by cantilevering a sharp tip over the surface of a sample and measuring the deflection of the tip in response to the atomic-scale features of the sample surface. AFM images are typically acquired in contact mode, in which the tip is in contact with the surface, or in non-contact mode, in which the tip is held above the surface. AFM is a powerful tool for investigating the Nanoworld.
What is STM?
- STM is an acronym for “scanning tunneling microscope”. STM is a type of electron microscope that uses a sharp metal tip to scan a surface and create a 3D image of that surface. STM can be used to study the atomic structure of materials, including metals, semiconductors, and insulators.
- STM is also used to fabricate nanostructures, such as nanotubes and nanowires. STM was invented in 1981 by Gerd Binnig and Heinrich Rohrer at the IBM Zurich Research Laboratory. STM won the Nobel Prize in Physics in 1986.
- STM operates by scanning a sharp metal tip over a surface. When the tip gets close to the surface, electrons can tunnel through the vacuum between the tip and the surface. The current flowing through the tunneling junction is proportional to the height of the tip above the surface.
- By mapping the current as a function of tip position, STM can create a 3D image of the surface with atomic resolution. STM can be used to study surfaces at room temperature or at cryogenic temperatures. STM can also be used to study surfaces in high vacuum or in ambient conditions.
Difference between AFM and STM
AFM and STM are two of the most commonly used techniques in nanotechnology. AFM (atomic force microscopy) is a type of scanning probe microscopy that uses a sharp tip to image the surface of a sample at the atomic scale. STM (scanning tunneling microscopy) is another type of scanning probe microscopy that uses an electrically conductive tip to image the surface of a sample at the atomic scale. AFM can be used to image non-conductive samples, while STM can only be used to image conductive samples. AFM is also capable of imaging samples in air, while STM requires the sample to be placed in a vacuum. Both AFM and STM are powerful tools for characterizing nanomaterials and for fabricating nanostructures.
Conclusion
The two microscopy techniques have different capabilities that make them better suited for certain tasks. AFM is good for imaging rough and soft surfaces while STM excels at imaging smooth surfaces. In addition, AFM can be used to measure the topography and stiffness of a surface, while STM can be used to measure the electrical properties of a surface.
