The team used a STM to create a transistor consisting of a single organic molecule and positively charged metal atoms, all positioned on the surface of an indium arsenide crystal. Kiyoshi Kanisawa, a physicist at NTT-BRL, used the growth technique of molecular beam epitaxy to prepare this surface.
Subsequently, the researchers assembled electrical gates from the metal ions, then placed the molecule at various desired positions close to the gates. Stefan Fölsch, a physicist at the Paul-Drude-Institut für Festkörperelektronik (PDI), who led the team, said: "The molecule is only weakly bound to the InAs template. So, when we bring the STM tip very close to the molecule and apply a bias voltage, single electrons can tunnel between template and tip. In our case, the charged atoms nearby provide the electrostatic gate potential that regulates the electron flow and the charge state of the molecule."
According to the team, the 'perfection and reproducibility' offered by these STM generated transistors will enable the exploration of elementary processes involving current flow through single molecules at a fundamental level. The researchers believe that understanding and controlling these processes – and the new kinds of behaviour to which they can lead – will be important for integrating molecule-based devices with existing semiconductor technologies.
Alongside PDI, the team included the Freie Universität Berlin, NTT Basic Research Laboratories and the US Naval Research Laboratory.
