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Suppression of twin domains in topological insulators

Topological insulators (Tis), such as Bi2Te3, have raised a great deal of attention because of their fascinating properties. Tis are insulators in bulk, but they have topologically protected surface states with a linear energy dispersion. Owing to the linear energy states, surface carriers are regarded quasi-relativistic particles, which may travel dissipationlessly across the surfaces with a spin-locked momentum.

Due to these properties, TIs may provide a fertile ground for carrying out basic research as well as exploiting them for future device applications. We have investigated the nucleation process of Bi2Te3 on Si(111) substrates, grown by means of molecular beam epitaxy in the van der Waals (vdW) growth mode. We found out that the Bi2Te3 crystals usually form twin domains, which are completely suppressed by growing the epilayers at low growth rates. To explain this phenomenon, we have calculated the vdW potentials of the two domains. It turns out that the suppression of twin domains is only understood by a vdW interaction of the Bi2Te3 film with the first Si atom layer underneath the substrate surface. These results have been recently published in Journal of Crystal Growth & Design:

Pole figure plot around the (105) reflection of Bi 2Te3 filmPole figure plot around the (105) reflection of Bi 2Te3 film. Only a single domain is present on the surface


Dr. Gregor Mussler,