Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 98: Electronic Structure Theory
HL 98.9: Vortrag
Freitag, 30. März 2012, 11:45–12:00, EW 202
Tight binding in cylindrical coordinates for the electronic states of Si/Ge rolled-up nanotubes — •Giovanni Pizzi1, Michele Virgilio2,3, Giuseppe Grosso2,3, Suwit Kiravittaya4, and Oliver G. Schmidt4 — 1Theory and Simulation of Materials, École Polytechnique Fédérale de Lausanne, Switzerland — 2NEST, Istituto Nanoscienze-CNR, Italy — 3Dipartimento di Fisica, Università di Pisa, Italy — 4Institute for Integrative Nanosciences, IFW Dresden, Germany
We have extended the sp3d5s* tight-binding model to the case of cylindrical symmetry in order to study the electronic states of multiwall rolled-up nanotubes, under the assumption of discrete rotational symmetry around the tube axis. We discuss the modifications that have to be applied to the standard tight-binding model so as to take into account the effects of the curvature on the hopping energies and on the spin-orbit coupling.
The input equilibrium positions of the atoms are obtained by means of continuum elasticity theory [1], and the electronic bands and states can be obtained with the code that we have developed for zincblende-like structures, using the parameters of Ref. [2]. The electronic band structure, the degeneracy liftings and the valley splitting in the conduction band of rolled-up Si/Ge nanotubes are discussed as an application.
[1] M. Grundmann, Appl. Phys. Lett. 83, 2444 (2003).
[2] Y. M. Niquet, D. Rideau, C. Tavernier, H. Jaouen, and X. Blase, Phys. Rev. B 79, 245201 (2009).