Fig. 4: IR-SNOM and electron transport characterization of ABC-TLG and ABA-TLG.
From: Large-area epitaxial growth of curvature-stabilized ABC trilayer graphene
a Schematic of IR-SNOM for characterization of ABC-TLG on a SiO2 substrate. b, d AFM topography image of TLG flakes showing uniform heights across the entire flake except along wrinkles (white lines). The height scale is 2 nm. c, e Corresponding IR-SNOM image of the TLG flake in b and d, ABA-TLG and ABC-TLG show different infrared contrasts, which are absent in the topography image. c has primarily armchair domain walls, and e has primarily zigzag domain walls. (contrast scale: 1.43 V in c and 2.20 V in e). Green arrows in c indicate correlated wrinkles and ABA-ABC domain walls. f R–VTG characteristics of CVD ABC-TLG at 1.8 K. Each curve was measured with a fixed VBG ranging from −120 V to 100 V (20 V steps). The on/off ratio increases with VBG due to the band gap opening of ABC-TLG. The inset shows a schematic of the dual-gated TLG device. g R–VTG characteristics of CVD ABA-TLG at 1.8 K. Each curve was measured with a fixed VBG ranging from −80 V to 100 V (20 V steps). The net doping (n-type or p-type) varied from device to device42, depending on details of the fabrication process in which charged impurities are introduced.
