Transport and Noise properties of silicon and carbon one-dimensional devices

In this thesis, we study fundamental properties of transport and noise in quasi-one dimensional (1D) devices, with particular attention to carbon-based devices. The thesis has two main themes. The first theme is shot noise in 1D transistors based on carbon nanotubes(CNTs) and silicon nanowires (SNWs), where the reduced number of carriers in the channel, make the device extremely sensitive to single charge fluctuations. We present a novel method for the computation of the shot noise power spectral density in quasi-1D conductors electrostatically controlled by a gate electrode, including the effects of both Coulomb interaction and Pauli exclusion among charge carriers. We show that significant deviations are obtained with respect to the case when only Pauli exclusion is taken into account by means of the Landauer-Buttiker formula. The second theme is mobility in graphene nanoribbons. The state-of-the art GNRs present indeed many scattering sources, which put limitations on electron transport. Among them defects, in the bulk and at the edge, impurities, phonon scattering and surface phonon scattering due to the polar nature of gate dielectrics used in such devices, strongly degrade mobility with respect to 2D graphene flakes. By means of statistical simulations performed on a large ensemble of GNRs with different occurrences of spatial distributions of non-idealities, we conclude that mobility in the state-of-the-art GNRs is mainly limited by line-edge roughness. We also focus on understanding phonon-limited mobility, which represents the ideal mobility achievable at a given temperature. We demonstrate that a large improvement in the state-of-the-art GNR mobility by a factor 10 can be achieved, but with a significant suppression when depositing GNRs on high-k polar dielectrics, losing all the advantages with respect to silicon-based technology.