Spectroscopic ellipsometry on Si/SiO{sub 2}/graphene tri-layer system exposed to downstream hydrogen plasma: Effects of hydrogenation and chemical sputtering

In this work, the optical response of graphene to hydrogen plasma treatment is investigated with spectroscopic ellipsometry measurements. Although the electronic transport properties and Raman spectrum of graphene change after plasma hydrogenation, ellipsometric parameters of the Si/SiO2/graphene tr...

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Bibliographic Details
Published in:Applied physics letters 2015-01, Vol.106 (1)
Main Authors: Eren, Baran, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, Fu, Wangyang, Marot, Laurent, Calame, Michel, Steiner, Roland, Meyer, Ernst
Format: Article
Language:English
Subjects:
ABSORPTION
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
ELECTRIC CONDUCTIVITY
ELLIPSOMETRY
EV RANGE
GRAPHENE
HYDROCARBONS
HYDROGEN
HYDROGEN IONS
HYDROGENATION
LAYERS
LIGHT TRANSMISSION
PLASMA
RAMAN SPECTRA
SILICA
SILICON OXIDES
SPUTTERING
SURFACES
VISIBLE RADIATION
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Summary:In this work, the optical response of graphene to hydrogen plasma treatment is investigated with spectroscopic ellipsometry measurements. Although the electronic transport properties and Raman spectrum of graphene change after plasma hydrogenation, ellipsometric parameters of the Si/SiO2/graphene tri-layer system do not change. This is attributed to plasma hydrogenated graphene still being electrically conductive, since the light absorption of conducting 2D materials does not depend on the electronic band structure. A change in the light transmission can only be observed when higher energy hydrogen ions (30 eV) are employed, which chemically sputter the graphene layer. An optical contrast is still apparent after sputtering due to the remaining traces of graphene and hydrocarbons on the surface. In brief, plasma treatment does not change the light transmission of graphene; and when it does, this is actually due to plasma damage rather than plasma hydrogenation.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4905597