Shrinking the size of a bulk metal into nanoscale leads to the discreteness of electronic energy levels, the so-called Kubo gap δ. Renormalization of the electronic properties with a tunable and size-dependent δ renders fascinating photon emission and electron tunneling. In contrast with usual three-dimensional (3D) metal clusters, here we demonstrate that Kubo gap δ can be achieved with a two-dimensional (2D) metallic transition metal dichalcogenide (i.e., 1T′-phase MoTe2) nanocluster embedded in a semiconducting polymorph (i.e., 1H-phase MoTe2). Such a 1T′/1H MoTe2nanodomain resembles a 3D metallic droplet squeezed in a 2D space which shows a strong polarization catastrophe while simultaneously maintaining its bond integrity, which is absent in traditional δ-gapped 3D clusters. The weak screening of the host 2D MoTe2leads to photon emission of such pseudometallic systems and a ballistic injection of carriers in the 1T′/1H/1T′ homojunctions which may find applications in sensors and 2D reconfigurable devices.
PACS 73.22.-f -Electronic structure of nanoscale materials and related systems PACS 73.63.-b -Electronic transport in nanoscale materials and structures PACS 61.46.-w -Structure of nanoscale materials Abstract -Based on the tight-binding method and density functional theory, band structures and transport properties of T-graphene nanoribbons are investigated. By constructing and solving the tight-binding Hamiltonian, we derived the analytic expressions of the linear dispersion relation and Fermi velocity of Dirac-like fermions for armchair T-graphene nanoribbons. Multiple Dirac points, which are triggered by the mirror symmetry of armchair T-graphene nanoribbons, are observed. The number and positions of multiple Dirac points can be well explained by our analytic expressions. Tight-binding results are confirmed by the results from density functional calculations. Moreover, armchair T-graphene nanoribbons exhibit negative differential resistance, whereas zigzag T-graphene nanoribbons have linear current-bias voltage characteristics near the Fermi level.
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