Graphene nanoribbons display an imperfectly understood transport gap. We measure transport through nanoribbon devices of several lengths. In long (>/=250 nm) nanoribbons we observe transport through multiple quantum dots in series, while shorter (</=60 nm) constrictions display behavior characteristic of single and double quantum dots. New measurements indicate that dot size may scale with cons...

We study the properties of flat bands that appear in a heterostructure composed strands different widths graphene armchair nanoribbons. One is reminiscent one appears pristine nanoribbons and has its origin quantum mechanical destructive interference effect, dubbed ``Wannier orbital states'' by Lin et al. Phys. Rev. B 79, 035405 (2009). The additional found these heterostructures, some reasonab...

We report on theoretical investigation of graphene based Field Effect Transistor (FET) structures for resonant absorption of terahertz (THz) radiation by the plasmons excited in the high sheet concentration and high carrier mobility active layers. Metallic grating gates with varying periods were used to couple the THz radiation into the plasmons in the active region of the devices. Such grating...

We determine the stability, the geometry, the electronic, and magnetic structure of hydrogen-terminated graphene-nanoribbon edges as a function of the hydrogen content of the environment by means of density functional theory. Antiferromagnetic zigzag ribbons are stable only at extremely low ultravacuum pressures. Under more standard conditions, the most stable structures are the mono- and dihyd...

We demonstrate the controlled tuning of the electronic band structure of large-arrays of graphene nanoribbons (GNRs) by chemical functionalization. The GNR arrays are synthesized by substrate-controlled metal-assisted etching of graphene in H2 at high temperature, and functionalized with different molecules. From Raman spectroscopy and carrier transport measurements, we found that 4-nitrobenzen...

The present paper casts light upon the performance of an armchair graphene nanoribbon (AGNR) field effect transistor in the presence of one-dimensional topological defects. The defects containing 5-8-5 sp(2)-hybridized carbon rings were placed in a perfect graphene sheet. The atomic scale behavior of the transistor was investigated in the non-equilibrium Green's function (NEGF) and tight-bindin...

Stimulated by recent advances in isolating graphene, the authors discovered that a quantum dot can be trapped in a Z-shaped graphene nanoribbon junction. The topological structure of the junction can completely confine electronic states. By varying the junction length, the authors can alter the spatial confinement and the number of discrete levels within the junction. In addition, a quantum dot...

Zigzag graphene nanoribbons (ZGNRs) are expected to serve as the promising component in the all-carbon spintronic device. It remains challenging to fabricate a device based on ZGNRs with high spin-filter efficiency and low experimental complexity. Using density functional theory combined with nonequilibrium Green's function technique, we studied the spin-dependent transport properties of the ta...