A nanoscale single-molecule amplifier and its consequences

Our ability to manipulate atoms and molecules on an individual basis has opened a new experimental frontier that makes feasible the quest for single molecular-scale devices as successors to the transistor. Here, we discuss our realization of the first amplifier using a single fullerene molecule less than 1 nm in diameter as the active element. This C/sub 60/ molecular device works by electromechanical modulation of virtual resonance quantum mechanical tunneling. The equivalent of the grid is achieved by the purely mechanical action of compressing the C/sub 60/ cage voltage. This action reversibly changes the internal electronic structure of the molecule, increasing its conductance in a continuous manner. The first embodiment provides experimental verification with a measured voltage gain of five. The implications of these results indicate a new approach to electronics on the nanoscale, working in a new transport regime for the three-terminal devices. Going beyond these experiments, we discuss possible approaches of creating single-molecule devices and the advantages they promise.