Electronic properties and carrier dynamics in layered materials
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Authors
Wang, Han
Issue Date
2017-12
Type
Electronic thesis
Thesis
Thesis
Language
ENG
Keywords
Physics
Alternative Title
Abstract
Since the fabrication of graphene in 2004, layered materials such as transition metal dichalcogenides and black phosphorus have attracted significant attention due to their intriguing physical properties and promising applications in nanoelectronics, photonics, sensing, energy storage, and optoelectronics. By assembling different monolayer materials into functional multilayer structures, dangling bond-free van der Waals (vdW) heterojunctions with atomically sharp interface can be designed and built. To further promote the applications of layered material and vdW heterojunctions, it is highly desirable to have a deep understanding of their physical properties. In this work, with density functional theory (DFT) method and time-dependent DFT (TDDFT) method, we study the intrinsic defects in TiS2, the stacking pattern of phosphorene homojunction and ultrafast charge transfer in MoS2/WS2 heterojunction. In the study of layered battery material TiS2, interstitial Ti defect is found to be the origin of metallic conductivity. After a complete search of different stacking pattern of phosphorene homojunctions, we identify a new metastable stacking, named Aδ stacking, and develop a band coupling theory to explain the band splitting in vdW vertical junctions. The hole transfer dynamics in MoS2/WS2 is simulated with TDDFT method. The mechanism of ultrafast hole transfer in this system is revealed based on a two-level model. The hole transfer dynamics is studied with a nonlinear dynamics theory. A critical phenomenon is observed in this system and successfully explained by the movement of lines of fixed points.
Description
December 2017
School of Science
School of Science
Full Citation
Publisher
Rensselaer Polytechnic Institute, Troy, NY