Transport behavior and weak adhesion of quantum confined epitaxial Bi and Bi1-xSbx films

Abstract

Novel devices, such as those based on principles of spin and magnetization instead of traditional electronic transport, necessitate the development of new materials systems. Bismuth (Bi) is a promising materials systems for these applications due to its high mobility, large spin-orbit interaction and metallic surface states which exhibit Rashba spin-splitting. In addition, Bi exhibits a thickness dependent band gap due to quantum size effects occurring at uniquely long length scales (>100nm) due to its large de Broglie wavelength. This allows the metallic surface states to be isolated from the bulk in the band gap. Alloying Bi with antimony (Sb) to create Bi1-xSbx allows access to topologically non-trivial surface states which have the aforementioned qualities associated with Bi, as well as added protection against backscattering and non-magnetic perturbation. In addition, the non-trivial topology of Bi1-xSbx makes it a contender for topological quantum computing devices using Majorana fermions and braided states. In this thesis, we explore the transport properties of Bi and Bi1-xSbx as the film thicknesses and alloy compositions are varied, providing a basis for custom design of these materials for specific applications. In addition, we report advances in the understanding of Bi and Bi1-xSbx growth on Si (111) through the measurement of their weak adhesion to the Si (111) substrate as well as the identification of (012) oriented crystal growth of Bi1-xSbx and the effect of this crystal structure transition on the transport properties of the films. Finally, we report the development of a dry transfer method which can be used to transfer high quality epitaxial Bi and Bi1-xSbx films to arbitrary substrates which may facilitate their integration into novel spin-based devicesElectrical and Computer Engineerin

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