Negative differential resistance in single-walled SiC nanotubes

Abstract

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...

Chirality Dependence of Electron Transport Properties of Single-Walled GeC Nanotubes

“…The NDR effect has also been reported recently in the I−V characteristics of the armchair SW-SiCNT, which has originated from the changes of density of states by the applied bias voltage. 19,20 The fluctuation of the transmission coefficient with the bias voltage is also found to be responsible for the NDR effect. 21,22 Zhang et al 23 behavior of silicon monatomic chain encapsulated in carbon nanotubes.…”

Silicon Carbide Nanotubes: From Finite Single-Walled to Infinite Multi-Walled

“…Song et al 80 investigated electronic transport properties of (4, 4) armchair SiCNT with the method combining NEGF and DFT and found the negative differential resistance (NDR) in the I-V curve of the SiCNT in the bias from +1 6 to +2 2 V. This comes from the variation in density of states (DOS) and the fluctuation of the transmission coefficient caused by the applied bias voltage. In another similar study on (7, 0) zigzag SiCNT, 78 it is reported that the current decreases when the bias is between +1 4 V and +1 7 V indicating that NDR appears in this bias range. NDR is an important property of the nanotubes for application in molecular switches and other electronic devices.…”

Electronic-Transport Properties of Single-Walled Zigzag SiGe Nanotubes

“…It has been found that the asymmetric couplings of CNTs with phenyl-ethyl oligomers and pyrrollo pyrrole are responsible for NDR . The origin of the NDR effect in the I–V curve of the armchair single-walled SiCNT has been identified as being due to changes of DOS by the applied bias voltage. , In some cases, the fluctuation of the transmission coefficient with the bias voltage gives rise to the NDR effect. , …”

“…39 The origin of the NDR effect in the I−V curve of the armchair single-walled SiCNT has been identified as being due to changes of DOS by the applied bias voltage. 40,41 In some cases, the fluctuation of the transmission coefficient with the bias voltage gives rise to the NDR effect. 42,43 The computed I−V curves of (4,0)−(7,0) SiGeNTs are given in Figure 5.…”