Physics Commons^™

The Study Of Excitons In 2d Novel Materials And Their Van Der Waals Heterostructures In The Magnetic Field, Anastasia Spiridonova

Dissertations, Theses, and Capstone Projects

This research focuses on the direct and indirect excitons in Rydberg states in monolayers, bilayers, and van der Waals heterostructures composed of 2D semiconductors in the presence of the external magnetic field. In our work, we report binding energies of direct and indirect excitons in Rydberg states, the energy contribution from the magnetic field to the binding energies of magnetoexcitons, and diamagnetic coefficients (DMCs) of magnetoexcitons.

We study isotropic materials: transition metal dichalcogenides, TMDCs (WSe₂, WS₂, MoSe₂, MoS₂), and Xenes (silicene, germanene, stanene), and anisotropic materials: phosphorene and transition metal trichalcogenides, TMTCs …

Using Superatomic Clusters And Charge Transfer Ligands To Control Electronic Characteristics Of Phosphorene Nanoribbons And Phosphorene Monolayer, Ryan Lambert

Theses and Dissertations

Phosphorene is a two-dimensional electron poor p-type semiconductor with high carrier mobility and great promise for applications in electronics and optoelectronics. As the main theme in this dissertation, the following work represents different investigations of various electronic properties associated with phosphorene. Most notable are the findings on charge transfer doping with metal-chalcogenide superatoms which displays novel control of the two most important properties of a semiconductor – the band gap energy and the nature of carriers. By tuning the width of the gap and p-/n-type character of conduction, we gain control over a material’s capacity to play a certain role …

Intercalation And High Pressure Studies Of Black Phosphorous - Pathways To Novel Materials And Physics., Manthila Chathurange Rajapakse

Electronic Theses and Dissertations

Discovery of graphene in 2004 initiated a new trend of materials known as two-dimensional (2D) materials which have exciting surface properties and anisotropies than their bulk counterparts. Phosphorene, which is the layered version of black phosphorous (BP) is one of the top 2D materials in terms of research interests and applications of the present day. Moving a step further, our interest is to understand the possibilities for structural modifications of phosphorene, by means of stimuli such as intercalation and high-pressure. It has been predicted by theoretical studies that these stimuli may lead to the formation of new structures and phases …

Optical And Collective Properties Of Excitons In 2d Semiconductors, Matthew N. Brunetti

Dissertations, Theses, and Capstone Projects

We study the properties of excitons in 2D semiconductors (2DSC) by numerically solving the Schr\"{o}dinger equation for an interacting electron and hole in the effective mass approximation, then calculating optical properties such as the transition energies, oscillator strengths, and absorption coefficients. Our theoretical approach allows us to consider both direct excitons in monolayer (ML) 2DSC and spatially indirect excitons in heterostructures (HS) consisting of two 2DSC MLs separated by few-layer insulating hexagonal boron nitride (h-BN). In particular, we study indirect excitons in TMDC HS, namely MoS₂, MoSe₂, WS₂, and WSe₂; …

Computational Prediction, Characterization, And Methodology Development For Two-Dimensional Nanostructures: Phosphorene And Phosphide Binary Compounds., Congyan Zhang

Electronic Theses and Dissertations

In this thesis, a comprehensive computational simulation was carried out for predicting, characterizing, and applications of two-dimensional (2D) materials. The newly discovered GaP and InP layers were selected as an example to demonstrate how to explore new 2D materials using computational simulations. The performance of phosphorene as the anode material of Lithium-ion battery was discussed as the example of the application of 2D material. Furthermore, the semi-empirical Hamiltonian for phosphorous and lithium elements have been developed for our future work on the application of phosphorus and lithium-based systems. The novel 2D materials of GaP and InP binary compounds were found …

Synthesis And Fundamental Property Studies Of Energy Material Under High Pressure., Meysam Akhtar

Electronic Theses and Dissertations

Recently, high-pressure science and technology has flourished and rapidly advanced to impact a wide domain of materials and physical sciences. One of the most substantial technological developments is the integration of samples at ultrahigh pressure with a wide range of in-situ probing techniques. Applications of extreme pressure have significantly enriched our understanding of the electronic, phonon, and doping effects on the newly emerged two-dimensional (2D) materials. Under high pressure, materials’ atomic volume radically decreases, and electronic density rises, which will lead to extraordinary chemical reaction kinetic and mechanisms. The promising capability of high pressure combine with the significance of novel …

Synthesis, Characterization, And Electronic Properties Of Novel 2d Materials : Transition Metal Dichalcogenides And Phosphorene., George Anderson

Electronic Theses and Dissertations

Scaling electronic devices has become paramount. The current work builds upon scaling efforts by developing novel synthesis methods and next generation sensing devices based on 2D materials. A new combination method utilizing thermal evaporation and chemical vapor deposition was developed and analyzed to show the possibilities of Transition Metal Dichalcogenide monolayers and heterostructures. The materials produced from the above process showed high degrees of compositional control in both spatial dimensions and chemical structure. Characterization shows controlled fabrication of heterostructures, which may pave the way for future band gap engineering possibilities. In addition, Phosphorene based field effect transistors, photodetectors, and gas …

An Improved Tight-Binding Model For Phosphorene, Kursti Delello

Honors Undergraduate Theses

The intent of this thesis is to improve upon previously proposed tight-binding models for one dimensional black phosphorus, or phosphorene. Previous models offer only a qualitative analysis of the band structure of phosphorene, and fail to fully realize critical elements in the electronic band structure necessary for transport calculations. In this work we propose an improved tight-binding model for phosphorene by including up to eight nearest-neighbor interactions. The efficacy of the model is verified by comparison with DFT-HSE06 calculations, and the anisotropy of the effective masses in the armchair and zigzag directions is considered.

First-Principles Studies Of Group Iv And Group V Related Two Dimensional Materials, Gaoxue Wang

Dissertations, Master's Theses and Master's Reports

Two dimensional (2D) materials have been extensively studied due to their novel properties and technologically important applications. Especially, the discovery of graphene has stimulated an avalanche of investigations to exploit its novel properties for applications at nanoscale. In the post-silicon era, graphene has been widely regarded as the most promising building blocks for the electronic devices. However, its metallic nature together with sensitivity to the environment leads to somewhat limited scope of applications. A finite band gap in a material is known to be essential for the fabrication of devices such as transistors. Such a limitation associated with graphene has …