How can a scanning tunneling microscope study the growth of one metal on another metal?

A scanning tunneling microscope (STM) studies the growth of one metal on another by leveraging its ability to image the atomic structure of surfaces with extreme precision.

Because the STM relies on the quantum mechanical phenomenon of tunneling, it can detect variations in tunneling current as a sharp probe tip scans just angstroms above a sample. This sensitivity allows researchers to document the epitaxial growth of various metal combinations, such as silver on gold or nickel on gold, at the atomic level.1

By mapping the density of electrons at the surface, the STM provides a topographical image that reveals how atoms arrange themselves during deposition. This capability enables scientists to observe the formation of atomic layers and terraces, providing detailed insights into the processes of surface diffusion and structural growth. Furthermore, the STM can operate under various environmental conditions, including high vacuum, which ensures the cleanliness of the sample surface during these delicate growth studies.1