Designing nanogadgets by interconnecting carbon nanotubes with zinc layers.

Using first-principles calculations we propose a new approach for the design of functional units obtained by interconnecting carbon nanotubes (CNTs) with different numbers of zinc layers. The theoretical investigations on electron transport properties of the resulting 1D heterojunctions containing CNTs with same or different chiralities (i.e., metallic or semiconducting) and one, two, or three zinc layers illustrate that the junctions with two semiconducting CNTs show semiconducting I-V characteristics while the junctions with two different CNT electrodes (metallic and semiconducting) show rectifying diode properties. The remarkable features emerging from this study is that the zinc layers behave as a momentum filter (near the Fermi energy the Bloch states having the same orbital character as the molecular states conduct well) when they are inserted within metallic CNT electrodes thereby providing 1D heterojunctions that can act as a wire-like, negative differential resistance (NDR), or varistor-type nanoscale device. Our results prove the idea that it is possible to design specific heterojunctions, which can select a conducting channel between two electrodes. Also, it is worth mentioning that in this study for the first time we have designed a nanoscale device with the characteristics of a varistor.