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%0 Thesis %A Weyrich, Christian Peter %T Electrical transport and magnetoresistance in MBE-grown 3D topological insulator thin films and nanostructures %I RWTH Aachen University %V Dissertation %C Aachen %M RWTH-2019-12205 %P 1 Online-Ressource (vii, 216 Seiten) : Illustrationen, Diagramme %D 2019 %Z Veröffentlicht auf dem Publikationsserver der RWTH Aachen University 2020 %Z Dissertation, RWTH Aachen University, 2019 %X The main focus of this thesis are the 3D topological insulators bismuth telluride (Bi2Te3) and antimony telluride (Sb2Te3), which have been known for several decades as narrow band gap insulators (about 150 meV) and for their thermoelectric properties. Since they were found to be topological insulators, scientific interest in the search for topologically protected surface states has increased and the electronic properties of these states have been studied widely using angle-resolved photoemission spectroscopy. These measurements confirmed the presence of metallic states within the band gap with almost linear dispersion relations and a Dirac point. Also, surface magneto-electric properties measured by scanning tunnelling microscopy have shown that the protected surface states in Sb2Te3 thin films are less sensitive to intrinsic defects. This promises charge carriers with a high mobility at the surface of these materials. However, all properties mentioned above are solely restricted to the topological protected surface states and thus require the bulk to be insulating in order to observe these effects in electrical transport. Otherwise they will be masked by the bulk conductance. This has proven to be a difficult task, since all the binary materials tend to be intrinsically doped due to the formation of crystal defects during growth. Therefore, the effort has concentrated on controlling the sample fabrication, carrier compensation doping, or alloying of intrinsic chalcogenide materials, in order to shift the Fermi level into the energy bandgap and closer to the Dirac zero gap point of the surface energy spectra. In this work, we analyze thin films grown by molecular beam epitaxy on Si(111)-substrates. First, the binary materials are introduced in terms of crystal structure, growth parameters, electronic structure and elemental distribution via investigations done by transmission electron spectroscopy, angle-resolved photoemission spectroscopy and atom probe tomography. This illustrates the intrinsic doping of Bi2Te3 and Sb2Te3 and the presence of different crystal domains due to the growth mechanism of the layered films. We also compare films grown on 100 mm wafers with samples of selectively grown films on pre-patterned substrates. These samples are precursors to the nanostructures that will be discussed in the last chapter. Next, two different approaches to engineer the Fermi level are presented. Films of (Bi1-xSbx) %F PUB:(DE-HGF)11 %9 Dissertation / PhD Thesis %R 10.18154/RWTH-2019-12205 %U https://publications.rwth-aachen.de/record/775402