An international team consisting of researchers from the U.S. Naval Research Laboratory and the NTT Basic Research Laboratories in Japan have developed a microscopic transistor made up of a single molecule and a small amount of atoms.
By positioning an organic molecule on a piece of indium arsenide, then placing charged metal atoms around it, the researchers were able to create the miniature device using a scanning tunneling microscope.
Stefan Fölsch, one of the researchers on the project, explains how it works in more detail:
“[T]he molecule is only weakly bound to the [surface]. So, when we apply a bias voltage… single electrons can tunnel between template and tip by hopping via nearly unperturbed molecular orbitals… the charged atoms nearby provide the electrostatic gate potential that regulates the electron flow and the charge state of the molecule.”
Essentially, the microscopic transistor acts pretty much like a normal transistor by providing a different output depending on the input voltage applied.
If you are interested in learning more about the research, check out Nature Physics.