Atomic-scale surface modifications using a tunnelling microscope

The desire to modify materials on the smallest possible scale is motivated by goals ranging from high-density information storage to the purposeful transformation of genetic material. Here we report an atomic-scale modification of the surface of a nearly perfect germanium crystal, effected by the tungsten tip of a tunnelling microscope. We believe this to be the smallest spatially controlled, purposeful transformation yet impressed on matter and we argue that the limit set by the discreteness of atomic structure has now essentially been reached. © 1987 Nature Publishing Group.