Controlled thermodynamics for tunable electron doping of graphene on Ir(111)

C. Struzzi, C. S. Praveen, M. Scardamaglia, N. I. Verbitskiy, A. V. Fedorov, M. Weinl, M. Schreck, A. Grüneis, S. Piccinin, S. Fabris, and L. Petaccia
Phys. Rev. B 94, 085427 – Published 25 August 2016
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Abstract

The electronic properties and surface structures of K-doped graphene supported on Ir(111) are characterized as a function of temperature and coverage by combining low-energy electron diffraction, angle-resolved photoemission spectroscopy, and density functional theory (DFT) calculations. Deposition of K on graphene at room temperature (RT) yields a stable (3×3) R30° surface structure having an intrinsic electron doping that shifts the graphene Dirac point by ED=1.30eV below the Fermi level. Keeping the graphene substrate at 80 K during deposition generates instead a (2×2) phase, which is stable until full monolayer coverage. Further deposition of K followed by RT annealing develops a double-layer K-doped graphene that effectively doubles the K coverage and the related charge transfer, as well as maximizing the doping level (ED=1.61eV). The measured electron doping and the surface reconstructions are rationalized by DFT calculations. These indicate a large thermodynamic driving force for K intercalation below the graphene layer. The electron doping and Dirac point shifts calculated for the different structures are in agreement with the experimental measurements. In particular, the K4s bands are shown to be sensitive to both the K intercalation and periodicity and are therefore suggested as a fingerprint for the location and ordering of the K dopants.

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  • Received 1 April 2016
  • Revised 18 July 2016

DOI:https://doi.org/10.1103/PhysRevB.94.085427

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

C. Struzzi1,2, C. S. Praveen3, M. Scardamaglia2, N. I. Verbitskiy4,5, A. V. Fedorov6,7,8, M. Weinl9, M. Schreck9, A. Grüneis6, S. Piccinin3, S. Fabris3,*, and L. Petaccia1,†

  • 1Elettra Sincrotrone Trieste, Strada Statale 14 km 163.5, 34149 Trieste, Italy
  • 2Chimie des Interactions Plasma Surface (ChIPS), University of Mons, 7000 Mons, Belgium
  • 3Consiglio Nazionale delle Ricerche (CNR)–Istituto Officina dei Materiali (IOM) DEMOCRITOS, and Scuola Internazionale di Studi Superiori Avanzati (SISSA), Via Bonomea 265, I-34136, Trieste, Italy
  • 4Faculty of Physics, University of Vienna, Strudlhofgasse 4, A-1090 Vienna, Austria
  • 5Department of Materials Science, Moscow State University, Leniskie Gory 1/3, 119991 Moscow, Russia
  • 6II Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany
  • 7Institute for Solid State Research, IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany
  • 8St. Petersburg State University, St. Petersburg 198504, Russia
  • 9Institut für Physik, Universität Augsburg, D-86135 Augsburg, Germany

  • *Corresponding author: fabris@democritos.it
  • Corresponding author: luca.petaccia@elettra.eu

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Issue

Vol. 94, Iss. 8 — 15 August 2016

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