Theoretical Investigation of Ballistic Electron Transport in Au and Ag Nanoribbons
Sushil Kumar and R.K. Moudgildownload PDF
Abstract. We have systematically investigated the ballistic electron transport in gold and silver nanoribbons using first principle methods. The electronic structure calculation is carried out using the “density functional theory” (DFT) within the “SIESTA” code. While the electronic transport is studied using the “non-equilibrium Green’s function” (NEGF) method combined with the “Landauer-Buttiker” (LB) approach. We have explored the transport along both the armchair (AC) and zigzag (ZZ) directions. Interestingly, both elements turn semiconducting in the AC-configuration, and their band gap oscillates with increasing width of the nanoribbon. On the other hand, nanoribbons retain metallic character in the ZZ-configuration, with a quantized electrical conductance 4G0 for sufficiently small width and temperatures as high as nearly 200 K; G0=2e2/h, is the elementary quanta of electrical conductance. At zero bias, electronic thermal conductance in each system increases non-linearly with temperature. More is the width of nanoribbons, more is the electronic contribution to heat transport. Further, to assess the utility of nanoribbons in thermoelectric devices, we have calculated the room-temperature Seebeck coefficient S. It is found to evince an oscillatory structure as a function of electrochemical potential μ of electrodes, with pronounced peaks (nearly -118 μV/K in the narrowest gold nanoribbon considered) in the AC-configuration. The maximum S achieved is seen to be comparable to the atomic chains of these elements in linear, ladder and zigzag topologies, suggesting practical importance of nanoribbons as thermoelectric sensors in nanoelectronic devices.
Electron Transport, Nanoribbons, DFT, NEGF, Thermoelectric
Published online 3/25/2022, 7 pages
Copyright © 2022 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Sushil Kumar and R.K. Moudgil, Theoretical Investigation of Ballistic Electron Transport in Au and Ag Nanoribbons, Materials Research Proceedings, Vol. 22, pp 28-34, 2022
The article was published as article 5 of the book Functional Materials and Applied Physics
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