▎ 摘　　要

Extraordinary properties of graphene such as its extremely high room-temperature electron mobility and thermal conductivity make this material appealing for many electronic and sensor applications. The absence of the energy band-gap in graphene's electronic spectrum motivates investigation of graphene nano-ribbons in which the electronic "transport gap" regime can be achieved when the width of the nano-ribbons is sufficiently small. The exact physical origin of the "transport gap" and its dependence on the width and the shape of graphene edges are still the subjects of debates. Here we report the calculations of the electron transport in graphene nano-ribbons. The method used for this study is based on the non-equilibrium Greens function method and the density functional theory. We focus our analysis on the possibility to open the band gap, induce the gap states via defects and on controlling the electrical conductivity by the chemical and physical means. Specifically, we varied the width of the hydrogen saturated zigzag graphene nano-ribbon and studied its effect on the current-voltage characteristics. It has been observed that the width of the ribbons affects the current-voltage characteristics considerably. The transport properties of graphene nanoribbon such as Seebeck coefficient, Hall coefficient have been extracted from our calculations. Our results also show that the graphene zigzag nano-ribbons exhibit nonlinear behavior of the current-voltage characteristics owing to the overlapping of pi* and pi bands near the Fermi level. The obtained results are important for the proposed electronic and optoelectronic applications of graphene nano-ribbons.