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Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 36: Posters: Bio/organic Molecules on Surfaces, Graphene, Solid/liquid interfaces, Metal Substrates, Electronic Structure Theory

O 36.97: Poster

Tuesday, April 1, 2014, 18:30–22:00, P1

Bandgap engineering in two-dimensional heterostructures — •Filip Anselm Rasmussen and Kristian Sommer Thygesen — Department of Physics, Technical University of Denmark, Kongens Lyngby, Denmark

Since the discovery of single layer graphene the search for other two-dimensional materials that might have equally interesting properties has begun. Contrary to graphene these materials may be anything from metals to large-gap insulators. Especially the possibility of combining materials with different band gaps may be useful for some applications like field-effect transistors and solar cells. Previously is has been shown that when a molecule comes in close proximity of a metal its energy levels shifts due to increased screening from the metal. To investigate if such an effect is also present in extended two-dimensional systems we have performed first principles calculations on heterostructures consisting of metal-2D insulator-2D semiconductor layers, to estimate the effect of screening from the metal on the semiconductor band gap. To include the effect of the long-range Coulomb interaction we have calculated the quasiparticle energies using the non-self-consistent G0W0 approximation and we find that the semiconductor band gap decreases from its vacuum value when brought in close proximity of a metal. This shows that it is possible to engineer the band gap of the 2D semiconductor by varying the number of insulating spacer layers.

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