Investigation on transport characteristics of metal-graphene nanoribbon interfaces Sandeep Kumar Ch, Raja G, Penchalaiah P E-mail:sandeep4442@gmail.com
Center for Nanotechnology Research, VIT University, Vellore-632014, Tamilnadu, India
Model Design:
Abstract: We study the transmission spectrum between Graphene nanoribbon (GNR) and Nickel (Ni) metal contacts. The transmission spectrum is calculated by varying contact area, temperature of armchair-GNR and zigzag-GNR with hydrogen (H) termination using covalent bond approach. The calculations will be performed using
Results and Discussion:
we calculate the transmission spectrum for
The following structures are modeled using
different types of graphene nanoribbon, interface length at
ATOMISTIX TOOL KIT where the structure is periodic along
various temperatures. We noted that the system with greater
A,B directions and heterogeneous along C direction. The left
bonding area i.e., 8A° has less transmission coefficient than with
and right electrodes were different with electrode area of 12A°.
less bonding are 4A°.
Here, green color represents Nickel, grey for Carbon and white for Hydrogen.
semi-empirical method (Extended Huckle Theory). (a) Keywords: Graphene nanoribbon, transmission spectrum. (b) Figure 2: Transmission coefficient of Zigzag GNR-Ni interface (a) represents 8A° (b) with 4A° with different temperatures.
Introduction:
(c)
Graphene attracts enormously due to its unique properties in electronics devices. Graphene based devices
(d)
are more prominent for very high speed applications[1,2]. GNR have one-dimensional structure with honey comb structure in two dimensional carbon lattices, which
(e)
Figure 3: Transmission coefficient of Armchair GNR-Ni interface (a) represents 8A° (b) 4A° with different temperatures.
are stripes on graphene sheet[3]. GNRs exhibits different electronic properties due to its various edge termination
(f)
structures. The metallic contacts play a major role in electronics transport at nano-scale range[2-6,8]. The parameters
(g)
involved in electron transport between metal and graphene are
Figure 4: Transmission spectrum of Chiral (2,2) GNR-Ni 4A° interface with various temperatures.
temperature, orientation, length, width, type and interfacial (h)
area of GNR.
Conclusion: Thus, we presented here transmission
In this letter, we calculated transmission spectrums
spectrum, between metal-GNR contacts with effect of covalent bond formation at the interface junctions. GNR forms a strong covalent bond with nickel at 2A° [1]adsorption length.
Figure 1: Side view along B-C plane and top view along A-C plane were demonstrated here. (a,b) indicates the side view of Z-
At different interface lengths, temperatures
GNR on Ni(111) with an overlap of 8A° and 4A°. (c,d) represent
the transmission coefficient was calculated using semi-empirical
the top view of the same. Similarly (e,f) shows the side view of A-
method. The transmission coefficient was calculated along C-
GNR on Ni(111) with an overlap of 8A° and 4A° and (g,h)
direction and the structure was periodic along other directions.
represents the topview.
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of
different Graphene nanoribbon structures
interface with metal. The system with large bonding area with metal has less transmission coefficient when compared with the system which has less bonding area.
References: [1] K Stokbro, M Engelund, and A Blom, Phys.Rev B 85, 165442(2012) [2] S. B Lopez, M. Vanevic, M. Kindermann, and M. Y. Chou, Phys. Rev. Lett. 104,076807(2010) [3] E Kan, Z Li and J Yang Graphene nanoribbon Geometric, Electronic, and Magnetic properties [4] P. A. Khomyakov, G. Giovannetti, P. C. Rusu, G. Brocks, J. vanden Brink, and P. J. Kelly, Phys. Rev. B 79, 195425 (2009) [5] J. Maassen, W. Ji and H. Guo, Appl.Phys.Lett.97,142105 (2010) [6] Q.Ran, M. Gao, X. Guan, Y.Wang, and Z. Yu Appl. Phys. Let 94, 103511 (2009) [7] The transport calculations were performed with ATOMISTIX TOOL KIT, version 12.2.2 [http://quantumwise.com/documents/manuals] [8]F. Xia, V. Perebeinos, Y.-M. Lin, Y. Wu, and P. Avouris, Nat. Nanotechnology. 6, 179(2011)