Atomic-scale movement induced in nanoridges by scanning tunneling microscopy on epitaxial graphene grown on 4H-SiC(0001)

Abstract

Nanoscale ridges in epitaxial multilayer graphene grown on the silicon face of 4º off-cut 4H-SiC (0001) were found using scanning tunneling microscopy (STM). These nanoridges are only 0.1 nm high and 25-50 nm wide, making them much smaller than previously reported ridges. Atomic-resolution STM was performed near and on top of the nano-ridges using a dual scanning technique in which forward and reverse images are simultaneously recorded. An apparent 100% enlarged graphene lattice constant is observed along the leading edge of the image for both directions. Horizontal movement of the graphene, due to both an electrostatic attraction to the STM tip and weak bonding to the substrate, is thought to contribute to the results.

Tip-Enhanced Raman Scattering of the Local Nanostructure of Epitaxial Graphene Grown on 4H-SiC (0001̅)

“…54 This compression-induced ridge-forming mechanism is well-explained in many papers. 11,12,14,15 The AFM topology image in Figure 3a shows the ridge to have an ∼6 nm height and ∼150 nm width. Far-field Raman and TERS spectra shown in Figure 3b were obtained from seven points across the ridge.…”

“…To characterize nanostructures of graphene grown on the C-face and understand their forming mechanism, many groups have used atomic force microscopy (AFM), scanning tunneling microscopy (STM), ,, and angle-resolved photoemission spectroscopy (ARPES) to study the morphology, occurrence frequency, synthesis temperature dependence, and effects on band structure of the most common nanostructures, e.g., ridges and steps. Among several techniques, Raman spectroscopy is considered as an ideal technique for graphene characterization because it provides robust information about defects, − internal strain, − stacking configuration, , number of layers, ,− and doping. ,, There are some publications about using Raman spectroscopy to characterize nanostructures on epitaxial graphene with insightful results, e.g., the occurrences of defects in some types of nanostructures. ,, However, the spatial resolution of normal Raman spectroscopy is limited by the diffraction of light, generally no better than a few hundred nanometers.…”

“…Therefore, it is possible to use strain engineering to control and manipulate the nanostructures and produce interesting products such as large band gap graphene. 13 To characterize nanostructures of graphene grown on the Cface and understand their forming mechanism, many groups have used atomic force microscopy (AFM), 12 scanning tunneling microscopy (STM), 11,14,15 and angle-resolved photoemission spectroscopy (ARPES) 16 to study the morphology, occurrence frequency, synthesis temperature dependence, and effects on band structure of the most common nanostructures, e.g., ridges and steps. Among several techniques, Raman spectroscopy is considered as an ideal technique for graphene characterization because it provides robust information about defects, 17−21 internal strain, 22−26 stacking configuration, 27,28 number of layers, 27,29−32 and doping.…”

Self-Organized Platinum Nanoparticles on Freestanding Graphene

“…To learn about the height and the top surface topography of the Pt NPs, atomic-scale STM images were obtained. A typical filled-state, 12 nm × 12 nm STM image is shown in Figure 3a, revealing an artificially stretched honeycomb lattice 21 Vertical and horizontal line profiles, running through the center of Figure 3a along the lines shown in red and blue, were extracted from the image. The horizontal line profile is plotted in blue directly below the image, while the vertical line profile is plotted in red at the bottom.…”

“…To learn about the height and the top surface topography of the Pt NPs, atomic-scale STM images were obtained. A typical filled-state, 12 nm  12 nm STM image is shown in Figure 3a, revealing an artificially stretched honeycomb lattice 21 near a pair of large white features (indicating increased height). A white box marks the original location of the lower right inset and highlights the stretched honeycomb lattice, while the left inset was acquired far from the NPs and shows the normal lattice constant.…”