Confined CVD Synthesis and Temperature-Dependent Spectroscopic Properties of Bilayer Graphene Ribbon Arrays with Bifunctional Modulation of Adhesion Metal.

Bilayer graphene ribbons (GRs) hold great promise for the fabrication of next-generation nanodevices, thanks to unparalleled electronic properties, especially the tunable bandgap in association with twist angle, ribbon width, edge structure, and interlayer coupling. A common challenge in manufacturing bilayer GRs via templated chemical vapor deposition (CVD) approach is uncontrollable dewetting of micro- and nano-scaled patterned metal substrates. Herein, a confined CVD synthetic strategy of bilayer GR arrays is proposed, by utilizing the bifunctional Ni as a buffered adhesion layer to regulate the anisotropic dewetting of metal film in the V-groove and as a carbon-dissolution regulated metal to initiate the bilayer nucleation. Using CH as direct donor of C dimer species, high-quality bilayer GR arrays are synthesized on regular CuNi ribbons with twist angles at 900 °C, harnessing the non-equilibrium jointly induced by confined V-groove and C dimer species. The nucleation and growth mechanism of bilayer GR are investigated with density functional theory (DFT) calculations. The as-grown bilayer GRs display distinctive variable temperature Raman and photoluminescence properties. Our results contribute to a highly controllable technique for fabricating twisted bilayer GR arrays and deep insights into the optical properties of bilayer GRs for potential optoelectronics applications.