Negative differential resistance,rectifying performance and switching behaviour in carbon-chain based molecular devices |
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| Affiliation: | 1. Department of Condensed Matter Physics, National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe Shosse 31, Moscow 115409, Russia;2. Laboratory of Computational Design of Nanostructures, Nanodevices and Nanotechnologies, Research Institute for the Development of Scientific and Educational Potential of Youth, Aviatorov str. 14/55, Moscow 119620, Russia;3. CNRS, LAAS, 7 avenue du Colonel Roche, F−31400 Toulouse, France;4. Université de Toulouse, LAAS, F−31400 Toulouse, France;1. Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan, Iran;2. Department of Electrical and Computer Engineering, University of Kashan, Kashan, Iran;3. Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia;4. Department of Electrical Engineering, Pardis of Urmia University, Urmia, Iran;5. Nanotechnology Research Center, Nano electronic Research Group, Physics Department, Urmia University, Urmia, Iran;1. Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan;2. Institute for Quantum Chemical Exploration, Minato-ku, Tokyo 108-0022, Japan;3. Graduate School of Systems Engineering, Wakayama University, Sakaedani 930, Wakayama, Wakayama 640-8510, Japan;4. Faculty of Systems Engineering, Wakayama University, Sakaedani 930, Wakayama, Wakayama 640-8510, Japan;1. Department of Electrical Engineering, Indian Institute of Technology Kanpur, Kanpur, U.P. 208016, India;2. Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur, U.P. 208016, India;3. Department of Physics, Indian Institute of Technology Kanpur, Kanpur, U.P.208016, India;1. Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao, 066004, PR China;2. State key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, 066004, PR China |
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| Abstract: | Using non equilibrium Green's function formalism coupled with density functional theory, we carry out electronic transport calculation in two types of molecular devices, one constructed by linear monoatomic carbon chain (···C–C–C–C ···) and the other by two carbon chains capped with a phenyl ring (···C–C–Ph–C–C···), sandwiched between two z-shape electrodes, constructed by zigzag-armchair-zigzag (zz-ac-zz) graphene nanoribbons (GNRs). The potential difference between the z-shape contacts can be varied by employing an external d.c. voltage source. Thus, one may observe the variation of conductivity through the channels. The current–voltage (I–V) characteristics of the proposed resistors show N-type negative differential resistance (NDR), within a particular voltage region. The figure of merit or PVR (peak to valley) ratio (Ipeak/Ivalley) gets significantly increased, on capping the chains with phenyl ring. A higher value of PVR in I–V characteristics enhances the possibility of applications utilizing NDR. The calculated I–V characteristic is asymmetric and the rectification ratio is found to be 7, in case of the linear carbon chain.The rectification ratio R(V) = I(V)/I(−V) is an important parameter which determines, its suitability as rectifying device. It has been demonstrated that on varying the conformation of the phenyl ring with respect to the plane of electrodes, the transport properties of the system can be modulated. Interestingly, I–V characteristics are asymmetric and show dual NDR peaks in perpendicular conformation of the phenyl ring, with respect to the electrodes in the (···C–C–Ph–C–C···) system. The figure of merit is found to be respectively 8 and 51 for the first and second NDR regions. The later value is extremely high, making it an excellent candidate for potential applications. Moreover, the multi peak NDR device may be widely used in multiple-valued logics. Only a limited number of multiple NDR peak molecular-based nano systems have so far been reported, which are quite complex; by contrast the present system seems to be quite simple. The physical phenomenon of NDR was explained in the light of molecular projected self-consistent Hamiltonian (MPSH) and also the evolution of the frontier molecular orbitals (HOMO–LUMO) as well as transmission under various external bias voltages. |
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| Keywords: | Mono atomic carbon chains I–V characteristics Transmission spectrum NEGF-DFT Rectification ratio Multi switching |
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