Dielectric Surface Charge Engineering for Electrostatic Doping of Graphene

ACS Applied Electronic Materials, vol. 2, pp. 1235–1242

Abstract

Abstract Controlling the doping level in graphene during integration into silicon CMOS compatible devices is an open challenge. In general, the doping level in graphene is influenced via substrate interactions, metal contacts, and encapsulation layers. Here, we demonstrate a method to control the Fermi level in graphene through transfer onto ionic-doped oxide surfaces. The substrates were prepared to this end by diffusion of ammonia and aluminum on the oxide surface, which induces positive (NSiO+) and negative (AlSiO–) charges on the oxide layer. Van der Pauw measurements show that the charge neutrality or Dirac voltage in graphene can be shifted from about −60 V (n = −8.62 × 1012 cm–2) on standard SiO2 to about 13 V (n = 2.17 × 1012 cm–2) on negatively doped SiO2 layers by manipulating the surface charge. Hall measurements show that the electron mobility in graphene transferred on an as-grown oxide surface is higher than for graphene on a doped oxide because of additional scattering centers. Transfer line method measurements show that the contact resistance between graphene and nickel electrodes varies in average from 683.3 Ω·μm on SiO2 to 1046.6 Ω·μm on negatively doped SiO2 and that it depends on both the substrate surface charge and on graphene sheet resistance. Ionic-doped oxide surfaces are generally temperature-stable with respect to front- and back-end-of-the-line semiconductor manufacturing. The method presented here allows adjustments of the surface charge density of the substrate, and thus in graphene, which cannot be realized by organic or metallic functionalization. Therefore, the method may be suitable for engineering graphene-based devices and circuits, in particular, for applications that require complementary devices or a specific position of the Fermi level in graphene, for example, to adjust contact resistivity, sheet resistance, or sensor sensitivity.

Authors 10

1. Sebastian Wittmann Aachen Chair of Electronic Devices

   Infineon Technologies (Germany) · RWTH Aachen University

   Affiliation as printed

   Infineon Technologies AG , Wernerwerkstrasse 2 , ,

   RWTH Aachen University , , Otto-Blumenthal-Straße 2 , ,

   Chair of Electronic Devices, RWTH Aachen University, Otto-Blumenthal-Straße 2, 52074 Aachen, Germany

   Infineon Technologies AG, Wernerwerkstrasse 2, 93049 Regensburg, Germany

2. Fabian Aumer

   Infineon Technologies (Germany)

   Affiliation as printed

   Infineon Technologies AG , Wernerwerkstrasse 2 , ,

   Infineon Technologies AG, Wernerwerkstrasse 2, 93049 Regensburg, Germany

3. Doris Wittmann

   Infineon Technologies (Germany)

   Affiliation as printed

   Infineon Technologies AG , Wernerwerkstrasse 2 , ,

   Infineon Technologies AG, Wernerwerkstrasse 2, 93049 Regensburg, Germany

4. Stephan Pindl

   Infineon Technologies (Germany)

   Affiliation as printed

   Infineon Technologies AG , Wernerwerkstrasse 2 , ,

   Infineon Technologies AG, Wernerwerkstrasse 2, 93049 Regensburg, Germany

5. Stefan Wagner Aachen AMO GmbH

   AMO (Germany)

   Affiliation as printed

   AMO GmbH , Otto-Blumenthal-Straße 25 , ,

   AMO GmbH, Otto-Blumenthal-Straße 25, 52074 Aachen, Germany

6. Amit Gahoi Aachen Chair of Electronic Devices

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University , , Otto-Blumenthal-Straße 2 , ,

   Chair of Electronic Devices, RWTH Aachen University, Otto-Blumenthal-Straße 2, 52074 Aachen, Germany

7. Eros Reato Aachen AMO GmbH Chair of Electronic Devices

   AMO (Germany) · RWTH Aachen University

   Affiliation as printed

   AMO GmbH , Otto-Blumenthal-Straße 25 , ,

   RWTH Aachen University , , Otto-Blumenthal-Straße 2 , ,

   AMO GmbH, Otto-Blumenthal-Straße 25, 52074 Aachen, Germany

   Chair of Electronic Devices, RWTH Aachen University, Otto-Blumenthal-Straße 2, 52074 Aachen, Germany

8. Melkamu Belete Aachen Chair of Electronic Devices

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University , , Otto-Blumenthal-Straße 2 , ,

   Chair of Electronic Devices, RWTH Aachen University, Otto-Blumenthal-Straße 2, 52074 Aachen, Germany

9. Satender Kataria Aachen Chair of Electronic Devices

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University , , Otto-Blumenthal-Straße 2 , ,

   Chair of Electronic Devices, RWTH Aachen University, Otto-Blumenthal-Straße 2, 52074 Aachen, Germany

10. Max C. Lemme corresponding Aachen AMO GmbH Chair of Electronic Devices

    AMO (Germany) · RWTH Aachen University

    Affiliation as printed

    AMO GmbH , Otto-Blumenthal-Straße 25 , ,

    RWTH Aachen University , , Otto-Blumenthal-Straße 2 , ,

    AMO GmbH, Otto-Blumenthal-Straße 25, 52074 Aachen, Germany

    Chair of Electronic Devices, RWTH Aachen University, Otto-Blumenthal-Straße 2, 52074 Aachen, Germany