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O: Fachverband Oberflächenphysik

O 32: 2D Materials I: Structure and Electronic Properties

O 32.2: Vortrag

Dienstag, 8. März 2016, 10:45–11:00, H24

Structural, thermodynamic and electronic properties of two-dimensional SiC, SiGe, and GeC alloys — Ivan Guilhon¹, Friedhelm Bechstedt², •Ronaldo Rodrigues Pela^1,3, Marcelo Marques¹, and Lara Kuhl Teles¹ — ¹Instituto Tecnológico de Aeronáutica, São José dos Campos, Brazil — ²Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität, Jena, Germany — ³Humboldt-Universität zu Berlin, Institut für Physik and IRIS Adlershof, Berlin, Germany

We investigate structural, thermodynamic, electronic properties of 2D binary alloys made from graphene, silicene and germanene by means of density functional theory calculations and a statistical method that accounts for disorder and compositional effects. The GGA-1/2 method [1] is used in electronic properties calculations to approximately include quasiparticle corrections. Si_1−xGe_x is the only stable alloy at usual growth temperatures. In Ge_1−xC_x, strong distortions of the lattice lead to a pronounced tendency for phase separation. Si_1−xC_x presents an ordered structure with composition x=0.5 stable up to T≈ 1000 K. While Si_1−xGe_x and Ge_1−xC_x are found to have vanishing band gaps, Si_1−xC_x has, around x=0.5, an appreciable band gap, which decreases exponentially with the growth temperature from ∼ 2.2 eV at 300 K to ∼ 1.2 eV at 900 K [2].

[1]: Phys. Rev. B 78, 125116 (2008); [2]: Phys. Rev. B 92, 075435 (2015).

Acknowledgments: “Conselho Nacional de Desenvolvimento Científico e Tecnológico” (CNPq), “Coordenação de Aperfeiçoamento de Pessoal de Nível Superior” (CAPES) and “Alexander von Humboldt Stiftung”.