Atoms and surfaces

Think about it; every time you touch something solid you touch the surface. Any time something like light wants to penetrate a material it has to first get past the surface. This picture shows atoms on a surface of silicon. It was taken using a scanning tunneling microscope. This works by putting a sharp metal tip near the surface. A small voltage between the tip and the surface makes a current flow across the tip-surface gap. This current depends very sensitively upon the tip-surface distance. As the tip is moved across the surface it might hit a bump - an atom and the current goes up slightly. By recording where the tip has been and what the current was we can build up a contour map of the atoms on a surface.

We use our STM to look at how materials grow on semiconductor surfaces. This is important because metals grown on semiconductors are found in the little circuit boards in most electronic devices. When electricity passes from the metal to the semiconductor the interface region might have an effect on the current. Knowing how well materials grow on surfaces helps to clarify this. This is just one corner of surface science, whose influence stretches far and wide and whose applications involve multi billion $ industries.