Efficient gating of epitaxial boron nitride monolayers by substrate functionalization

A. Fedorov, C. S. Praveen, N. I. Verbitskiy, D. Haberer, D. Usachov, D. V. Vyalikh, A. Nefedov, C. Wöll, L. Petaccia, S. Piccinin, H. Sachdev, M. Knupfer, B. Büchner, S. Fabris, and A. Grüneis

Phys. Rev. B 92, 125440 – Published 28 September 2015

Abstract

Insulating hexagonal boron nitride monolayers $(h BN)$ are best known for being resistant to chemical functionalization. This property makes $h BN$ an excellent substrate for graphene heterostructures, but limits its application as an active element in nanoelectronics where tunable electronic properties are needed. Moreover, the two-dimensional–materials' community wishes to learn more about the adsorption and intercalation characteristics of alkali metals on $h BN$ , which have direct relevance to several electrochemistry experiments that are envisioned with layered materials. Here we provide results on ionic functionalization of $h BN / metal$ interfaces with K and Li dopants. By combining angle-resolved photoemission spectroscopy (ARPES), x-ray photoelectron spectroscopy, and density functional theory calculations, we show that the metallic substrate readily ionizes the alkali dopants and exposes $h BN$ to large electric fields and band-energy shifts. In particular, if $h BN$ is in between the negatively charged substrate and the positive alkali ion, this allows us to directly study, using ARPES, the effects of large electric fields on the electron energy bands of $h BN$ .

Received 15 May 2015
Revised 4 August 2015

DOI:https://doi.org/10.1103/PhysRevB.92.125440

Authors & Affiliations

A. Fedorov^1,2,3,*, C. S. Praveen^4,*, N. I. Verbitskiy^1,5,6, D. Haberer⁷, D. Usachov³, D. V. Vyalikh^3,8, A. Nefedov⁹, C. Wöll⁹, L. Petaccia¹⁰, S. Piccinin⁴, H. Sachdev¹¹, M. Knupfer², B. Büchner², S. Fabris^4,†, and A. Grüneis^1,‡

¹II. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany
²Institute for Solid State Research, IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany
³St. Petersburg State University, St. Petersburg 198504, Russia
⁴Theory@Elettra Group, CNR-IOM DEMOCRITOS and SISSA, via Bonomea 265, 34136 Trieste, Italy
⁵Faculty of Physics, University of Vienna, Strudlhofgasse 4, A-1090 Vienna, Austria
⁶Department of Materials Science, Moscow State University, Leninskiye Gory 1/3, 119992 Moscow, Russia
⁷Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
⁸Institute of Solid State Physics, Dresden University of Technology, D-01062 Dresden, Germany
⁹Institute für Funktionelle Grenzflächen (IFG), Karlsruher Institut für Technologie (KIT), Hermann-von-Helmoltz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
¹⁰Elettra Sincrotrone Trieste, Strada Statale 14 km 163.5, 34149 Trieste, Italy
¹¹Max-Planck-Institut für Polymerforschung, Ackermannweg 10, D-55128 Mainz, Germany

^*Authors contributed equally to this work.
^†fabris@democritos.it
^‡grueneis@ph2.uni-koeln.de

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Vol. 92, Iss. 12 — 15 September 2015

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