Transport

The research on transport properties of nanoelectronic devices has become a worldwide effort due to the possibility to fabricate structures at the nanometer scale. Metal-Oxyde-Semiconductor transistors with channel lengths as small as 10 nm are now being actively studied both theoretically and experimentally [464]. Remarkable experiments have been performed to measure the current I through single-quantum systems, such as molecules [465–472] or semiconductor quantum dots [249, 473–478]. In these experiments, the molecules or the quantum dots are connected to metallic electrodes under bias φ using scanning tunneling microscopy tips [249, 465, 468, 476], nanometersize electrodes [469, 477] or break junctions [470, 472]. Measurements display features arising from the quantum states of the system and from Coulombic effects (see Chap. 4). Peaks in the conductance dI/dφ characteristics are attributed to resonant tunneling through discrete levels. Also, semiconductor nanocrystals can be assembled to form artificial materials with interesting transport properties [479–481].