Functionalized Germanene as Emerging Nanomaterials

Tuesday, 7 October 2014: 08:30
Expo Center, 1st Floor, Universal 7 (Moon Palace Resort)
J. Li (Dept of Mat. Sci. and Eng., University of Pennsylvania), D. Datta (Brown University), and V. B. Shenoy (Depts of Mat. Sci. and Eng. & Mech. Eng. and App. Mech., University of Pennsylvania)
Using first principle calculations, we propose functionalized germanene (GeX, X=H,F,Cl,Br,I,OH,CH3) as emerging nanomaterials. While germanene has no band gap, complete functionalization with H induces band gap of around 1.80 eV. 50% H functionalization shows a dangling band at the Fermi level. While GeI is a 2D Topological Insulators (TI); GeH,GeF,GeCl and GeBr can be transformed into TI by applying strain.The methyl-functionalized two-dimensional germanium monolayer sheets have been synthesized with a facile, one-step metathesis approach from CaGe2 crystals. We find that tensile strain can induce topological phase transition with band inversion at Gamma point. The band gap opened by spin-orbit coupling in this quantum spin Hall insulator can be as large as 0.1 eV ample for practical applications at room temperature.