Electrostatics of metal-graphene interfaces: sharp p-n junctions for electron-optical applications

Ferney A. Cherves, David Jiménez, Jaime E. Santos, Peter Bøggild, Jose M. Caridad*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Creation of sharp lateral p-n junctions in graphene devices, with transition widths w well below the Fermi wavelength λF of graphene’s charge carriers, is vital to study and exploit these electronic systems for electron-optical applications. The achievement of such junctions is, however, not trivial due to the presence of a considerable out-of-plane electric field in lateral p-n junctions, resulting in large widths. Metal-graphene interfaces represent a novel, promising and easy to implement technique to engineer such sharp lateral p-n junctions in graphene field-effect devices, in clear contrast to the much wider (i.e. smooth) junctions achieved via conventional local gating. In this work, we present a systematic and robust investigation of the electrostatic problem of metal-induced lateral p-n junctions in gated graphene devices for electron-optics applications, systems where the dependence of the width w of the created junctions is not only determined by the metal used but also on external factors such as device geometries, dielectric environment and different operational parameters such as carrier density and temperature. Our calculations demonstrate that sharp junctions (w << λF) can be achieved via metal-graphene interfaces at room temperature in non-encapsulated devices surrounded by dielectric media with low relative permittivity (<10). In addition, we show how specific details such as the separation distance between metal and graphene and the permittivity of the gap in-between plays a critical role when defining the p-n junction, not only defining its width w but also the energy shift of graphene underneath the metal. These results can be extended to any two-dimensional (2D) electronic system doped by the presence of metal clusters and thus are relevant for understanding interfaces between metals and other 2D materials.
Original languageEnglish
JournalNanoscale
Volume11
Issue number21
Pages (from-to)10273-10281
Number of pages9
ISSN2040-3364
DOIs
Publication statusPublished - 2019

Keywords

  • Graphene
  • Electron optics
  • Sharp pn junctions
  • Metal-graphene interfaces

Cite this

Cherves, Ferney A. ; Jiménez, David ; Santos, Jaime E. ; Bøggild, Peter ; Caridad, Jose M. / Electrostatics of metal-graphene interfaces: sharp p-n junctions for electron-optical applications. In: Nanoscale. 2019 ; Vol. 11, No. 21. pp. 10273-10281.
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abstract = "Creation of sharp lateral p-n junctions in graphene devices, with transition widths w well below the Fermi wavelength λF of graphene’s charge carriers, is vital to study and exploit these electronic systems for electron-optical applications. The achievement of such junctions is, however, not trivial due to the presence of a considerable out-of-plane electric field in lateral p-n junctions, resulting in large widths. Metal-graphene interfaces represent a novel, promising and easy to implement technique to engineer such sharp lateral p-n junctions in graphene field-effect devices, in clear contrast to the much wider (i.e. smooth) junctions achieved via conventional local gating. In this work, we present a systematic and robust investigation of the electrostatic problem of metal-induced lateral p-n junctions in gated graphene devices for electron-optics applications, systems where the dependence of the width w of the created junctions is not only determined by the metal used but also on external factors such as device geometries, dielectric environment and different operational parameters such as carrier density and temperature. Our calculations demonstrate that sharp junctions (w << λF) can be achieved via metal-graphene interfaces at room temperature in non-encapsulated devices surrounded by dielectric media with low relative permittivity (<10). In addition, we show how specific details such as the separation distance between metal and graphene and the permittivity of the gap in-between plays a critical role when defining the p-n junction, not only defining its width w but also the energy shift of graphene underneath the metal. These results can be extended to any two-dimensional (2D) electronic system doped by the presence of metal clusters and thus are relevant for understanding interfaces between metals and other 2D materials.",
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year = "2019",
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language = "English",
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pages = "10273--10281",
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Electrostatics of metal-graphene interfaces: sharp p-n junctions for electron-optical applications. / Cherves, Ferney A.; Jiménez, David; Santos, Jaime E.; Bøggild, Peter; Caridad, Jose M.

In: Nanoscale, Vol. 11, No. 21, 2019, p. 10273-10281.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Electrostatics of metal-graphene interfaces: sharp p-n junctions for electron-optical applications

AU - Cherves, Ferney A.

AU - Jiménez, David

AU - Santos, Jaime E.

AU - Bøggild, Peter

AU - Caridad, Jose M.

PY - 2019

Y1 - 2019

N2 - Creation of sharp lateral p-n junctions in graphene devices, with transition widths w well below the Fermi wavelength λF of graphene’s charge carriers, is vital to study and exploit these electronic systems for electron-optical applications. The achievement of such junctions is, however, not trivial due to the presence of a considerable out-of-plane electric field in lateral p-n junctions, resulting in large widths. Metal-graphene interfaces represent a novel, promising and easy to implement technique to engineer such sharp lateral p-n junctions in graphene field-effect devices, in clear contrast to the much wider (i.e. smooth) junctions achieved via conventional local gating. In this work, we present a systematic and robust investigation of the electrostatic problem of metal-induced lateral p-n junctions in gated graphene devices for electron-optics applications, systems where the dependence of the width w of the created junctions is not only determined by the metal used but also on external factors such as device geometries, dielectric environment and different operational parameters such as carrier density and temperature. Our calculations demonstrate that sharp junctions (w << λF) can be achieved via metal-graphene interfaces at room temperature in non-encapsulated devices surrounded by dielectric media with low relative permittivity (<10). In addition, we show how specific details such as the separation distance between metal and graphene and the permittivity of the gap in-between plays a critical role when defining the p-n junction, not only defining its width w but also the energy shift of graphene underneath the metal. These results can be extended to any two-dimensional (2D) electronic system doped by the presence of metal clusters and thus are relevant for understanding interfaces between metals and other 2D materials.

AB - Creation of sharp lateral p-n junctions in graphene devices, with transition widths w well below the Fermi wavelength λF of graphene’s charge carriers, is vital to study and exploit these electronic systems for electron-optical applications. The achievement of such junctions is, however, not trivial due to the presence of a considerable out-of-plane electric field in lateral p-n junctions, resulting in large widths. Metal-graphene interfaces represent a novel, promising and easy to implement technique to engineer such sharp lateral p-n junctions in graphene field-effect devices, in clear contrast to the much wider (i.e. smooth) junctions achieved via conventional local gating. In this work, we present a systematic and robust investigation of the electrostatic problem of metal-induced lateral p-n junctions in gated graphene devices for electron-optics applications, systems where the dependence of the width w of the created junctions is not only determined by the metal used but also on external factors such as device geometries, dielectric environment and different operational parameters such as carrier density and temperature. Our calculations demonstrate that sharp junctions (w << λF) can be achieved via metal-graphene interfaces at room temperature in non-encapsulated devices surrounded by dielectric media with low relative permittivity (<10). In addition, we show how specific details such as the separation distance between metal and graphene and the permittivity of the gap in-between plays a critical role when defining the p-n junction, not only defining its width w but also the energy shift of graphene underneath the metal. These results can be extended to any two-dimensional (2D) electronic system doped by the presence of metal clusters and thus are relevant for understanding interfaces between metals and other 2D materials.

KW - Graphene

KW - Electron optics

KW - Sharp pn junctions

KW - Metal-graphene interfaces

U2 - 10.1039/C9NR02029B

DO - 10.1039/C9NR02029B

M3 - Journal article

VL - 11

SP - 10273

EP - 10281

JO - Nanoscale

JF - Nanoscale

SN - 2040-3364

IS - 21

ER -