Imaging layer number and stacking order through formulating Raman fingerprints obtained from hexagonal single crystals of few layer graphene

Abstract

Quantitative mapping of layer number and stacking order for CVD-grown graphene layers is realized by formulating Raman fingerprints obtained on two stepwise stacked graphene single-crystal domains with AB Bernal and turbostratic stacking (with ~30°interlayer rotation), respectively. The integrated peak area ratio of the G band to the Si band, A(G)/A(Si), is proven to be a good fingerprint for layer number determination, while the area ratio of the 2D and G bands, A(2D)/A(G), is shown to differentiate effectively between the two different stacking orders. The two fingerprints are well formulated and resolve, quantitatively, the layer number and stacking type of various graphene domains that used to rely on tedious transmission electron microscopy for structural analysis. The approach is also noticeable in easy discrimination of the turbostratic graphene region (~30° rotation), the structure of which resembles the well known high-mobility graphene R30/R2(±) fault pairs found on the vacuum-annealed C-face SiC and suggests an electron mobility reaching 14,700 cm(3) V(-1) s(-1). The methodology may shed light on monitoring and control of high-quality graphene growth, and thereby facilitate future mass production of potential high-speed graphene applications.

Highly sensitive transient absorption imaging of graphene and graphene oxide in living cells and circulating blood

“…1a) exhibited a 2D/G peak ratio of 2.2 and a symmetric 2D band with full width half maximum (FWHM) of 30 cm −1 . 2D/G peak ratio measured from 10 Raman spectra from the single layer areas was found to be 2.3 ± 0.3, which confirms the single layer assignment1148. In addition, the intensity of G band is almost proportional to the number of graphene layers49, which confirmed the existence of double layer domain (position 2 in Fig.…”

Programmed Synthesis of Freestanding Graphene Nanomembrane Arrays

“…In particular, the I 2D /I G ratio decreases as the number of graphene layers increases. Peak positions of G and 2D bands, the I 2D /I G ratio and FWHMs of 2D bands of the Raman spectra of three devices that we tested here confirm the formation of multilayer graphene (see Supporting Information, Section S1) . The presence of a weak D‐band with CVD‐assisted grown graphene is expected because the laser spot (∼1 μm) is much larger than the size of a typical graphene domain (20–100 nm).…”

Configurable Three‐Dimensional Boron Nitride–Carbon Architecture and Its Tunable Electronic Behavior with Stable Thermal Performances

“…It is observed that the absence of D peak in the pure 3D‐C sample indicates the presence of high quality pristine graphene. The second‐order Raman band (2D band) can be used to estimate the number of layers of CVD‐grown graphene according to its relative intensity with respect to the G band (I 2D /I G ) . The intensity of the G band is about 4 times higher than the intensity of the 2D band (I 2D /I G ≈0.25), indicating multi‐layer graphene.…”