Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 105: Poster: Topological insulators (with MA/O)

HL 105.4: Poster

Donnerstag, 3. April 2014, 17:00–20:00, P1

Topological Insulator Nanowires by Chemical Vapour Deposition — •Piet Schönherr and Thorsten Hesjedal — Department of Physics, Clarendon Laboratory, University of Oxford, Oxford, OX1 3PU, United Kingdom

Topological insulators (TIs) are a new state of quantum matter which insulates in the bulk and conducts on the surface. The study of bulk TIs has been hindered by high conductivity inside the bulk, arising from crystalline defects. Such problems can be tackled through compositional engineering or the synthesis of TI nanomaterials. We combined both approaches in a systematic study of various growth parameters to achieve uniform, high purity nanowires with high substrate coverage.

The highlight of this study is the development of a new growth route for nanowires, based on a TiO2 catalyst rather than the conventional Au. Comparative studies demonstrate that Au significantly contaminates the nanowires, whereas TiO2 stays well separated. Details of the Au and TiO2-catalysed growth mechanism were investigated. For Au it was found that the growth mechanism is vapour-liquid-solid. For TiO2 nanoparticles, in contrast, the growth mechanism can be described in the vapour-solid scheme.

Nanowires of the doped compound (Bi0.78Sb0.22)2Se3 were studied using synchrotron radiation. It was discovered that the material mainly adopts an orthorhombic phase known from Sb2Se3. The Raman spectrum is reported and matched with the structural information for the first time. Further, a method to control the length and diameter of Bi2Se3 nanowires through laser-cutting was developed.

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