Fig. 2: Perfect alignment of top hBN and graphene using the neighboring graphite edge.

a Optical image of single-layer graphene connecting with a neighboring graphite edge. b G/hBN stack after alignment using the graphite edge of (a). The red line profiles the outline of 0° G/hBN and the green line profiles the outline of 30° G/hBN. c Spatial map of the FWHM of Raman 2D-band for the black dashed area in (b). d Single-layer graphene with one edge (white dashed line) has 60° with a neighboring graphite edge. e G/hBN stack after alignment using the graphite edge of (d). f Spatial map of the FWHM of Raman 2D-band for the black dashed area in (e). g Single-layer graphene without any connection with an adjacent graphite edge. h G/hBN stack after alignment using the graphite edge of (g). i Spatial map of the FWHM of Raman 2D-band for the black dashed area in (h). Scale bars, 20 µm (a, d, g); 5 µm (b, e, h); 2 µm (c, f, i). j Histogram of the FWHM of Raman 2D-band and twist angle for 20 moiré samples. The FWHM of ~20 cm⁻¹ (green color) corresponds to 30° G/hBN, and the FWHM of ~40 cm⁻¹ (red color) corresponds to 0° G/hBN. The FWHM of 20 moiré samples is larger than 40 cm⁻¹, as indicated by the horizontal dashed line, indicating that the accuracy of our technique is better than ~0.2°.