Extended Data Fig. 1: hBN-encapsulated graphene nanoribbon samples.
From: Evidence for chiral supercurrent in quantum Hall Josephson junctions
a, Schematic describing the uncertainty in the junction width δW (red lines) and length δL (vertical black dashed lines in the zoom). Horizontal black dashed lines indicate the uncertainty in the graphene width δWAFM from AFM imaging. Blue rectangles represent MoGe electrodes correctly aligned, dashed blue lines indicate the MoGe electrode position with a misalignment (δx, δy), which results in an uncertainty δWal on the graphene edges position. b, AFM picture for sample HV88, the encapsulated graphene is readily visible with contrast enhancement. c, Zoom on the graphene narrow part in (b), with the lithography pattern overlayed (Ti/Au lines in orange and MoGe electrodes in blue). Red lines indicate the total width uncertainty ± δW/2 around the graphene edges. d, AFM picture of the graphene nanoribbon of sample DP24 before hBN encapsulation. Inset: higher resolution AFM picture. The arrows indicate the nanoribbon width of 125 nm. e, AFM picture of sample DP24 after hBN encapsulation. The yellow arrows indicate the nanoribbon position. The lithography pattern is overlayed on the picture. The scale bars are 5 μm (b), 400 nm (c), 2 μm (d), 500 nm (d) inset, 500 nm (e). f, AFM picture of sample DP24 contact fabrication. The scale bar is 1 μm. g, h, Height profiles along the blue and green lines in the AFM image in f. The excess thickness on the contact edge results from the liftoff process of the MoGe.
