A two-probe system was established for a finite (7, 0) silicon carbide (SiC) nanotube coupled to Au (111) surfaces via Au-C bonds. Using the non-equilibrium Green function (NEGF) combined with density functional theory (DFT), the above system was studied for its electronic transport properties. Negative differential resistance (NDR) was observed when the bias voltage was greater than 1.4 V. Because the transport properties of the system were sensitive to the applied bias voltage, NDR might be caused by the fluctuation of the transmission coefficient with the bias voltage.non-equilibrium Green function, silicon carbide nanotube, transport properties, negative differential resistance Bulk silicon carbide (SiC) is a wide band-gap semiconductor and widely used in high-power, high-temperature electronic devices. Since the discovery of carbon atoms in tubular form [1] , named carbon nanotube (CNT), much work has been done. SiC nanotubes (SiCNTs) were recently synthesized via the reaction of SiO with multiwalled carbon nanotubes at different temperatures [2] . The stability and electronic structures of SiCNTs were studied with the ab initio method. The results show that single-walled SiCNTs are wide band-gap semiconductors independent of their helicity and radius, and they are more suitable than bulk SiC in the application of nano-electronic devices [3][4][5] .The transport properties of the SiCNTs are the foundation of their applications. The lack of investigations on the transport properties of the SiCNTs limits these applications. NDR is a useful property in electronic devices such as molecule switches. It has been observed in the measurements of the CNTs' transport properties and its mechanism has been studied theoretically [6][7][8][9] . It is meaningful to find out whether the (7, 0) SiCNT has the property of NDR or not.To study the electronic transport properties of the (7, 0) SiCNT, a two-probe system was established for a finite (7, 0) SiCNT coupled to two Au (111) electrodes via Au-C bonds (Figure 1), which can be divided into the left semi-infinite electrode, the center scattering region, and the right semi-infinite electrode. The center scattering region consists of a finite (7, 0) SiC nanotube and two (5×5) surface layers of the left and right electrodes. The electronic structures of the Au electrodes were considered to be the same as those of the bulk Au. The periodic boundary conditions were imposed in the directions parallel to the interface between the SiCNT and Au electrodes. The distance between the SiCNT and electrodes plays an important role in the transport properties of the two-probe system. In our calculations, the distance was set to 1.6 Å, which has been used in the study on the electronic transport properties of CNT heterojunction [10] .The electronic transport properties of the above system were studied with the method combining NEGF with DFT implemented in the TranSIESTA-C code and its latest version, Atomistix Toolkit 2.2 (ATK 2.2), which has been successfully applied to the study on the tr...
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