Abstract
We use micro-Raman spectroscopy to study strain in free-standing graphene monolayers anchored to SiN holes of non-circular geometry. We show that a uniform differential pressure load yields measurable deviations from hydrostatic strain, conventionally observed in radially symmetric microbubbles. A pressure load of 1 bar yields a top hydrostatic strain of ≈ 0.7% and a G± splitting of 10 cm−1 in graphene clamped to elliptical boundaries with axes 40 and 20 μm, in good agreement with the calculated anisotropy Δε ≈ 0.6% and consistently with recent reports on Grüneisen parameters. The implementation of arbitrary strain configurations by designing suitable boundary clamping conditions is discussed.
Highlights
Graphene displays a range of remarkable properties that have catalyzed—since its discovery in 20041—an impressive interest in the scientific community.[2]
Hydrostatic configurations were obtained and studied using circular holes and a uniform differential pressure load,[13,14,15] and the impact of strain was studied by micro-Raman spectroscopy.[16,17,18]
We demonstrate that markedly non-isotropic strain profiles can be obtained in free-standing graphene membranes that are clamped on an edge that is not radially symmetric and are subject to a vertical uniform load using a pressure difference between the two opposite faces of the graphene flake
Summary
Graphene displays a range of remarkable properties that have catalyzed—since its discovery in 20041—an impressive interest in the scientific community.[2]. We show that loaded elliptical membranes display Raman features that demonstrate the presence of an anisotropic component in the induced strain profile, in good agreement with what is expected with the studied geometry.
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