Stable and metallic borophene nanoribbons from first-principles calculations

Recently, borophene was reported to be produced on silver surfaces. We employed density functional theory and electronic transport calculations to investigate the stabilities, electronic structures and transport properties of borophene nanoribbons. The stability of a borophene nanoribbon increases with its width and only the lined-edged borophene nanoribbons are stable in the free-standing form. Such anisotropic stability dependence is ascribed to the large scale delocalization of pi electrons along the boron rows. In particular, all line-edge borophene nanoribbons undergo edge reconstructions, in which the out-of-plane bulking edge atoms are reconstructed to form quasi planar edge structures. Such edge reconstructions have not yet been reported, which is critical for the formation of boron nanostructrues. Subsequent electronic transport calculations based on a non-equilibrium Green's function indicated that line-edge borophene nanoribbons exhibit low-resistivity Ohmic conductance. Our results indicated that the line-edge borophene nanoribbons present remarkable properties (high thermal stabilities, Ohmic conductance with low electrical resistivity and good rigidities) and are promising for applications as one-dimensional electrical connections in compact nanoscale circuits.