Key Words single-molecule transistor, Coulomb blockade, electronic shell filling, Kondo resonance, inelastic tunneling, electron wave interference ■ Abstract Transport spectroscopy, a technique based on current-voltage measurements of individual nanostructures in a three-terminal transistor geometry, has emerged as a powerful new tool to investigate the electronic properties of chemically derived nanostructures. In this review, we discuss the utility of this approach using the recent studies of single-nanotube transistors as an example. Specifically, we discuss how transport measurements can be used to gain detailed insight into the electronic motion in metallic single-walled carbon nanotubes in several distinct regimes, depending on the coupling strength of the contacts to the nanotubes. Measurements of nanotube devices in these different conductance regimes have enabled a detailed analysis of the transport properties, including the experimental determination of all Hartree-Fock parameters that govern the electronic structure of metallic nanotubes and the demonstration of Fabry-Perot resonators based on the interference of electron waves.
INTRODUCTIONOptical spectroscopy has long served as the experimental tool of choice for investigating electronic and nuclear motions in atoms and molecules. In optical spectroscopy, the interaction between light and matter causes transitions between quantum states, and series of well-resolved spectral features are recorded as a function of the wavelength of light. The positions, intensities, and widths of the observed spectral features provide detailed information concerning the dynamics of electrons and nuclei in atoms and molecules. Optical spectroscopy has also been applied successfully to chemically derived nanostructures, such as nanocrystals (1-3), nanowires (4,5), and carbon nanotubes (6, 7), providing insight into the effects of quantum confinement on the electronic properties of these nanostructures.
LIANG BOCKRATH PARKOver the last decade, a new type of spectroscopy based on electron transport measurements, often termed transport spectroscopy, has emerged as a powerful tool for investigating electronic motions in chemical nanostructures. Originally developed for lithographically-defined quantum dots (8), transport spectroscopy is based on current-voltage measurements of a three-terminal transistorlike device in which a single chemical nanostructure bridges two electrodes, and a third gate electrode couples electrostatically to the nanostructure. The electronic conduction through such devices at sufficiently low temperatures is dictated by single-electron charging and energy level quantization (9). Plots of current as a function of bias voltage exhibit features that provide detailed information on quantum-level structures in chemical nanostructures that complements optical spectroscopy.To date, transport spectroscopy has been carried out for a variety of chemical nanostructures, including molecules (10-14), nanocrystals (15)(16)(17)(18)(19), nanowires (20,21), and si...