Fig. 3: Experimental and DFT calculated results of the edge states of 3 TBZGNR junctions with θ ≈ 90°.

a–c STS taken at the zigzag edges of three TBZGNR junctions. Insets in a–c are the STM images of the three junctions indicating where the STS were taken. Scale bar in insets: a 0.7 nm, b 0.76 nm, c 0.74 nm. The dI/dV signals only show a gap-like feature at the edge of junction A, while a pronounced peak near zero energy was shown in TBZGNR junctions B and C (as indicated by the red vertical dashed lines). The pronounced peak near zero energy distributed along the whole bottom edge of the TBZGNR junction B, as shown in b while distributed only in the vicinity of the corner of junction C, as shown in (c). The black vertical dashed lines highlight the STS peak positions above zero energy. d–f DFT-calculated PDOS for the edge atoms of the three TBZGNR Models A, B and C. The red and blue curves in d are the PDOS at the red and blue points shown in the inset. The grey shaded area represents the PDOS of the edge atoms in monolayer ZGNR. The curves labelled 1–5 in e, f are the PDOS for corresponding atoms 1–5 in the inset for Model B and Model C, respectively. The yellow-shaded areas highlight the PDOS peaks near zero energy. The red and black dashed lines indicate the peak energy position below and above zero energy correspondingly. The ribbon lying horizontally stands for the “top” ribbon in d–f. All models were structurally relaxed. The interlayer distances were optimized to be ~3 Å. Tunnelling parameters: a V_stab = −0.3 V, I_stab = 1.1 nA, V_osc = 0.5 mV; b V_stab = −0.3 V, I_stab = 1.0 nA, V_osc = 0.5 mV; c V_stab = −0.3 V, I_stab = 1.0 nA, V_osc = 0.7 mV.