Fig. 2: Multigate 9-AGNR transistors with SWNT electrodes.

a, Electronic dispersion relation of a representative M-SWNT (7,7) with sub-bands and zero bandgaps (left). Illustration of the discrete energy levels of the GNR and sharp DOS in the two SWNT electrodes (right). The sharp DOS peaks exhibit Van Hove singularities, which are associated with the sub-bands of the SWNT. Note that we indicate the barriers between the left SWNT electrode and GNR, and between the right SWNT electrode and GNR. The asymmetrical barriers are illustrated in practice. b, Similar illustration as a for a representative S-SWNT (7,6) with the same diameter as the M-SWNT in a. It has relatively more dense Van Hove singularities in the DOS and a finite bandgap. The electronic dispersion and DOS for SWNTs (7,7) and (7,6) are adapted from another work³³. Note that the chiralities of the SWNTs used for this work were not determined. c, Schematic of the device, including the measurement circuit. d, Optical image of a device with an overlay of the G-peak Raman intensity map coloured in red (532 nm laser, 1 mW power and 1 s integration time). Scale bar, 10 μm. e, Topographic AFM image showing the SWNT electrodes and gate layout of the device. High-resolution AFM characterization of a representative SWNT nanogap (~20 nm) defined by EBL (left). Scale bar, 20 nm. Topography profile across the SWNT (blue solid line) and gate electrodes (red solid line) with a 30 nm atomic-layer-deposited Al₂O₃ layer on top (middle). Scale bar, 100 nm. Profiles (blue and red solid lines) are taken along the blue and red dotted lines in the corresponding AFM image, respectively (right).