Negative differential resistance behavior of silicon monatomic chain encapsulated in carbon nanotubes

Abstract

Using nonequilibrium Green's functions in combination with density-functional theory (DFT), we investigated the electronic transport properties of the silicon monatomic chains (SiMCs) with different geometries which were induced by the encapsulation of the carbon nanotubes (CNTs). The encapsulated SiMCs, which were put inside (5,5), (6,6), (7,7) and (8,8) hydrogenated armchair CNTs, were coupled to two Au (1 0 0) nanoscale electrodes. The electronic transport property of an isolated finite SiMC was also studied to serve as a reference to our calculations. As the diameter of CNTs increases, the geometry structures of SiMCs changed. Calculated results show that the current-voltage (I-V) characteristics depend sensitively on the geometry structures of SiMCs and can be controlled by the size-selective encapsulation. Negative differential resistance (NDR) phenomena were observed within certain bias voltage ranges. A detailed analysis of the origin of NDR was carried out with the transmission spectrum, the spatial distribution of frontier molecular orbitals and the molecular projected self-consistent Hamiltonian (MPSH) states taken into consideration. These results indicated that the size-selective encapsulation of SiMCs in CNTs can become a possible candidate for designing the silicon-based nanoelectronic devices.