Uniaxial Strain Redistribution in Corrugated Graphene: Clamping, Sliding, Friction, and 2D Band Splitting

Abstract

Graphene is a promising material for strain engineering based on its excellent flexibility and elastic properties, coupled with very high electrical mobility. In order to implement strain devices, it is important to understand and control the clamping of graphene to its support. Here, we investigate the limits of the strong van der Waals interaction on friction clamping. We find that the friction of graphene on a SiO2 substrate can support a maximum local strain gradient and that higher strain gradients result in sliding and strain redistribution. Furthermore, the friction decreases with increasing strain. The system used is graphene placed over a nanoscale SiO2 grating, causing strain and local strain variations. We use a combination of atomic force microscopy and Raman scattering to determine the friction coefficient, after accounting for compression and accidental charge doping, and model the local strain variation within the laser spot size. By using uniaxial strain aligned to a high crystal symmetry direction, we also determine the 2D Raman Grüneisen parameter and deformation potential in the zigzag direction.

2D Raman band splitting in graphene: Charge screening and lifting of the K-point Kohn anomaly

“…3(a) for λ = 532 nm. The lower energy 2D 1 peak has a well-defined strain-induced slope of 1.7 ± 0.13, very close to the calculated value for uniaxial strain/compression in a random lattice direction 25 , 26 . The strain variation across the sample is on the order of ±0.1% which is small enough not to cause strain-induced peak-splitting 27 .…”

“…The red laser selects shorter q vectors through the DR mechanism and therefore has a significantly lower 2D energy than the green laser, as expected. Both data sets exhibit strain lines, indicating some compression 25 , 26 . We first consider Fig.…”

Measuring Interlayer Shear Stress in Bilayer Graphene

“…S12 [27], τ 1 is extracted with values in the range of 1-3 MPa and an average of 1.64 MPa (Fig. 5), in good agreement with previous reports for the graphene-SiO 2 interfaces (0.25-2 MPa) [51,52] and graphene-polymer interfaces (0.3-2.3 MPa) [43,53]. In contrast, for bilayer graphene, the shear deformation outside the hole is much more significant, owing to the weak shear resistance between the two graphene layers.…”

Scalable Synthesis of 2D Si Nanosheets

“…It is interesting to observe that friction on a‐SiNSs was noticeably lower than that on c‐SiNSs. This is contrary to the traditional trend where a disordered surface usually exhibits higher friction resulting in stronger energy dissipation . We suspect that this unusual behavior can be attributed to the lubrication effect of the in‐plane disordered wall or from the high mobility of surface atoms in amorphous Si .…”