Date of Award

1-1-2019

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Nanoscale Science and Engineering

Program

Nanoscale Sciences

Content Description

1 online resource (ix, 120 pages) : color illustrations

Dissertation/Thesis Chair

Bin Yu

Committee Members

Hassaram Bakhru, Mengbing Huang, Spyros Gallis, Bhaskar Nagabhirava

Keywords

Broadband, Graphene, Photodetector, Photodiode, Schottky Barrier, Topological Insulator, Topological insulators, Optical detectors, Nanostructured materials, Layer structure (Solids)

Subject Categories

Nanoscience and Nanotechnology

Abstract

Topological insulators are characterized by the presence of a finite energy gap in the bulk state and a conducting metallic surface state consisting of odd number of Dirac cones. The conducting surface states are along the edge boundaries, free from disorders and are protected by time reversal symmetry. The presence of Dirac cone leads to universal optical absorption phenomenon like graphene. This phenomenon of universal optical absorption leads to frequency independent photoexcitation of carriers. Bi2Te3, Sb2Te3 and Bi2Se3 belong to tetradymite topological insulators (TTI) family and are often referred to as 3D layered materials. Theoretical predictions characterize TTIs by low energy bulk gap (0.15 to 0.3 eV) and a single Dirac cone at the Γ point which is confirmed by angle-resolved photoemission spectroscopy experimental studies. The presence of Dirac cone is due to band inversion of valence and conduction band along the sample boundary caused by strong spin-orbit coupling.

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