29. A Faster STM
Keith Schwab
Keith C. Schwab, Physics, and research colleagues used an existing technique in an innovative way to make the scanning tunneling microscope (STM), which can image individual atoms on a surface, at least 100 times faster. The researchers made a simple adaptation based on a method of measurement currently used in nano-electronics. The STM uses quantum tunneling, the ability of electrons to “tunnel” across a barrier, to detect changes in the distance between a needlelike probe and a conducting surface. Researchers apply a tiny voltage to the sample and move the probe—a simple platinum-iridium wire snipped to end in a point just one atom wide—a few angstroms over the sample’s surface. By measuring changes in current as electrons tunnel between the sample and the probe, they can reconstruct a map of the surface topology down to the atomic level. Since its invention in the 1980s, the STM has enabled major discoveries in fields from semiconductor technology to nano-electronics. This innovative technique could also give STMs significant new capabilities, including the ability to sense temperatures in spots as small as a single atom and to detect changes in position as tiny as 0.00000000000001 meters: a distance 30,000 times smaller than the diameter of an atom.