Figure 1

Growth and characterizations of GNRs and CNTs. (a) Schematic of GNR and CNT growth on h-BN substrate. The growth starts at Fe-nanoparticles, where methane molecules can decompose into atomic carbon, serving as source for the GNRs and CNTs growth. (b) AFM topography image of an as-grown sample with both GNRs and CNTs on h-BN. The higher (brighter) line corresponds to CNTs, and the lower (blurred) ones correspond to GNRs. Bright dots are Fe-nanoparticles. (c,d) AFM topography images of turns in CNTs and GNRs. A CNT tends to produce gentle-curved bends (c), while a GNR tends to produce sharp corners (d). This is due to the difference in their stiffness. (e) Height profiles of a CNT (red) and a GNR (black), taken along the dash lines in panel (c) and (d). The diameter of a nanotube is apparently larger than the thickness of a nanoribbon. (f,g) AFM topography image of CNTs and GNRs and the corresponding near-field infrared image of the same area. CNTs exhibit stronger response (brighter) than GNRs in the near-field optical image due to CNTs’ stronger optical conductivity. (h) Illustration of a typical growth process. Scale bars: 500 nm in (b); 100 nm in (c,d,f,g).