The structures of Ge nanowires are studied by means of geometry optimization method in this paper. As the radii of carbon nanotubes increase, the structures of the Ge nanowires transform from a monoatomic chain to helical and multishell coaxial cylinders. The physical properties, such as density of states, transmission functions, current-voltage (I-V) characteristics, and conductance spectra (G-V) of optimized nanowires sandwiched between two gold contacts are also obtained. The transport properties of a carbon-coated Ge atomic chain are significantly different from those of Ge single atomic chain. Furthermore, some nonequilibrium properties of Ge nanowires are compared with those of Sn and Si nanowires.

Similar to the water wave on a pond caused by dropping a pebble, the formation of ripples is shown in a single layer graphene ͑SLG͒ when it is stroked by a C60 molecule, no matter whether the graphene is plane or corrugated. The controllable ripple in SLG is investigated by molecular dynamics simulations. Noticeable diffraction and interference of the ripples are observed. This study indicates that the ripple propagation in graphene can be used to detect defects.

A new and simple kind of heterostructure nanoelectronics, which are free of metal electrodes, is constructed by a boron nitride nanoribbon (BNNR) seamlessly connected between two pieces of graphene nanoribbons (GNRs). The electron transport properties of devices based on such GNR-BNNR-GNR heterostructures are systematically investigated. The effects of vacancy, chirality, width, and boundary of nanoribbons on the electron transport properties of these devices are discussed. Energy gaps over 1 eV are observed in the electron transmission spectra of devices composed of these heterojunctions, indicating their pronounced field effect transistor (FET) characters. Removing hydrogen atoms at the boron edge of zigzag BNNR can result in 100% electron spin polarization in the GNR-BNNR-GNR FET. This study has implications for developing high-performance monatomic layer nanoelectronics with simple heterojunctions.