Substrate polarization effect on the band gaps of one-dimensional semiconducting atomic wires

The dielectric screening induced modulation of the electronic structure of model SiH2 and GeH2 one-dimensional atomic wires is investigated using graphene as a prototypical substrate. A combination of first-principles density functional theory and many-body perturbation theory within the GW approximation is employed to investigate how the substrate alters the electronic structure of the weakly bounds wires. The quasiparticle GW band gaps of the atomic wires are reduced by ∼1 eV when supported by a graphene substrate. The band gap reduction is attributed to a change in the correlation energy of the frontier orbitals of the atomic wires due to the increased effective screening of the Coulomb interaction as a result of the polarization of the dielectric substrate. This work indicates that the band gaps of semiconducting nanowires composed of Si and Ge can be engineered via the interaction with the substrate in addition to conventional approaches such as adjusting size and crystal orientation.

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