Pedro Brandimarte

A tunable electronic beam splitter realized with crossed graphene nanoribbons

Journal of Chemical Physics - 2017    

Abstract

Graphene nanoribbons (GNRs) are promising components in future nanoelectronics due to the large mobility of graphene electrons and their tunable electronic band gap in combination with recent experimental developments of on-surface chemistry strategies for their growth. Here, we explore a prototype 4-terminal semiconducting device formed by two crossed armchair GNRs (AGNRs) using state-of-the-art first-principles transport methods. We analyze in detail the roles of intersection angle, stacking order, inter-GNR separation, GNR width, and finite voltages on the transport characteristics. Interestingly, when the AGNRs intersect at θ=60°, electrons injected from one terminal can be split into two outgoing waves with a tunable ratio around 50% and with almost negligible back-reflection. The split electron wave is found to propagate partly straight across the intersection region in one ribbon and partly in one direction of the other ribbon, i.e., in analogy with an optical beam splitter. Our simulations further identify realistic conditions for which this semiconducting device can act as a mechanically controllable electronic beam splitter with possible applications in carbon-based quantum electronic circuits and electron optics. We rationalize our findings with a simple model suggesting that electronic beam splitters can generally be realized with crossed GNRs.

Press release

Bibtex citation

@Article{Brandimarte2017,
  author    = {Pedro Brandimarte and Mads Engelund and Nick Papior and Aran Garcia-Lekue and Thomas Frederiksen and Daniel S{\'{a}}nchez-Portal},
  title     = {A tunable electronic beam splitter realized with crossed graphene nanoribbons},
  journal   = {Journal of Chemical Physics},
  year      = {2017},
  volume    = {146},
  number    = {9},
  pages     = {092318},
  issn      = {0021--9606},
  doi       = {10.1063/1.4974895},
  publisher = {AIP Publishing},
}

Key words

• electronic beam splitter
• graphene nanoribbons
• multi-terminal device
• density functional theory
• non-equilibrium Green's function