Band structure engineering in 3D topological insulators investigated by angle-resolved photoemission spectroscopy

Autor*innen

• Markus Eschbach

Parameter

• Lehrbücher
• Universitätslehrbücher

Mehr zum Buch

Three-dimensional topological insulators (3D TIs) represent a novel state of quantum matter, offering exciting prospects for spintronic devices due to their unique electronic properties. These materials feature an insulating energy gap in the bulk while exhibiting conductive, spin-polarized states at their surfaces, protected by time reversal symmetry and topology. However, for practical applications, it's essential to engineer the electronic band structure to position the Fermi level within the band gap, as many 3D TIs exhibit significant bulk conductivity. This thesis explores various methods to manipulate the Fermi level and electronic properties of thin films of common 3D TI materials, including Bi2Se3, Bi2Te3, and Sb2Te3, grown via molecular beam epitaxy. The surface electronic structure is analyzed using angle-resolved photoelectron spectroscopy. It highlights the successful creation of a vertical topological p-n junction in Sb2Te3/Bi2Te3/Si(111) heterostructures, demonstrating the ability to transition the surface of Sb2Te3 from p-type to n-type by adjusting the influence of the Bi2Te3 layer. The findings are supported by self-consistent solutions of the Schrödinger and Poisson equations. Additionally, the thesis investigates the crystal structure and electronic properties of the natural superlattice phase Bi1Te1, revealing it as a weak topological insulator, with surface states lacking measurable helical spin polarizat

• Sprache: Englisch
• Erscheinungsdatum: 2016