Field-effect modulation of the conductance of single molecules

Field-effect transistors based on two-component self-assembled monolayers o f conjugated and insulating molecules were prepared; the conductance throug h them can be varied by more than three orders of magnitude by changing the applied gate bias. With very small ratios of conjugated to insulating mole cules in the two-component monolayer, devices with only a few "electrically active" molecules can be achieved. At low temperatures, the peak channel c onductance is quantized in units of 2e(2)/h (where e is the electron charge and h is Planck's constant). This behavior is indicative of transistor act ion in single molecules. On the basis of such single-molecule transistors, inverter circuits with gain are demonstrated.