자료유형  

 학위논문

Control Number  

0017161679

International Standard Book Number  

9798384452874

Dewey Decimal Classification Number  

541

Main Entry-Personal Name  

Brinn, Rafaela Mendes.

Publication, Distribution, etc. (Imprint  

[S.l.] : University of California, Berkeley., 2024

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Physical Description  

165 p.

General Note  

Source: Dissertations Abstracts International, Volume: 86-03, Section: B.

General Note  

Advisor: Alivisatos, A. Paul;Ramesh, Ramamoorthy.

Dissertation Note  

Thesis (Ph.D.)--University of California, Berkeley, 2024.

Summary, Etc.  

요약This dissertation is composed of 7 chapters discussing optical studies performed in thin film samples. These studies are separated in two parts. Part I focuses on studies performed on quantum dot monolayer thin films while Part II discusses work on erbium doped ferroelectric thin films. Part I will have 4 chapters: Chapter 1 is an introductory chapter on quantum dots' structural and optical properties, Chapter 2 is a quantitative study on the recombination rates of QD thin films with different shell thicknesses, Chapter 3 will discuss incorporation of atomic dopants to engineer quantum dots of a specific size and energy and finally Chapter 4 will provide a brief conclusion on the work done as well as outlook on future avenues of controlling the photophysics of QD thin film. Part II will have 3 additional chapters: Chapter 5 will expand on fundamental concepts of rare-earth doped ferroelectric thin films, Chapter 6 will contain a study on tuning erbium emission via epitaxial strain engineering of the ferroelectric thin film matrix and Chapter 7 will contain concluding thoughts on this part of the dissertation and provide outlooks on potential strategies to further manipulate erbium emission. To briefly expand more on the projects discussed in Chapter 2,3,and 6.In Chapter 2, we measure the photoluminescence quantum yield of self-assembled quantum dot monolayer thin films and quantify their radiative and nonradiative rates. The recombination rates of core/shell quantum dot self-assembled monolayer superlattices are systematically compared to their colloidal solution counterparts. Both the radiative and nonradiative rates of these quantum dots were found to be enhanced in the thin film samples. The increase in nonradiative rate is expected and can be attributed to the stripping of ligands from the nanocrystal surface as well as energy transfer in close-packed solid-state samples. In contrast, the increase in radiative rate in the film reveals a change in the fundamental optical properties of quantum dot films, suggesting that the oscillator strength of the nanocrystals increases in the films compared to in solution. The increase in oscillator strength is likely due to changes in the organic ligand shell coverage and its effect on the electronic band structure of the quantum dot.In Chapter 3, we study exciton diffusion lengths in micron-sized superlattices where Te-doped CdSe:Te/CdS nanocrystals serve as the building blocks. These nanocrystals are synthesized colloidally with 5% of Te dopant stoichiometrically added during the seeded growth synthesis of wurtzite CdSe nanocrystals. Through this colloidal synthesis, we can make nanocrystals with a much broader and red-shifted emission than their undoped counterparts, proving that the Te-dopant has been successfully incorporated in the CdSe matrix. A thin hexagonal CdS shell is then grown around the Te-doped CdSe core forming a dot-in-plate (or nut in bolt) shape. Using elemental mapping techniques we characterize the distribution of elements in our CdSe:Te/CdS core/shell nanocrystals. Based on their shape, these nanocrystals can self-assemble into a highly ordered 2D superlattice structure with a heterogeneous energy landscape. Using Stimulated Emission Depletion (STED) microscopy, we measure the exciton diffusion lengths in these superlattices to elucidate the role of the Te-dopant in transport.In Chapter 6, we discuss how erbium doped materials are powerful candidates for quantum information sciences due to their long electron and nuclear spin coherence times, as well as telecom-wavelength emission. By selecting host materials with interesting, controllable properties, we introduce a new parameter that can be used to study Er3+ emission. In this work, we study erbium (Er3+)-doped PbTiO3 thin films. PbTiO3 is a well-studied ferroelectric material with known methods of engineering different domain configurations through epitaxial strain. Through changing the domain configurations of the PbTiO3 thin films, we create radically different crystal fields around the Er3+ dopant. This is resolved through changes in the Er3+ resonant fluorescence spectra, tying the optical properties of the defect directly to the domain configurations of the ferroelectic matrix. Additionally, a second set of peaks are observed for films with in-plane polarization. We hypothesize these results to be due to either the Er3+ substituting different sites of the PbTiO3 crystal or due to differences in charges between the Er3+ dopant and the original substituent ion. Understanding the relationship between the Er3+ emission and the epitaxial strain of the ferroelectric matrix lays the pathway for future optical studies of spin manipulation through altering ferroic order parameters.

Subject Added Entry-Topical Term  

Physical chemistry.

Subject Added Entry-Topical Term  

Nanotechnology.

Subject Added Entry-Topical Term  

Materials science.

Subject Added Entry-Topical Term  

Chemistry.

Index Term-Uncontrolled  

Exciton dynamics

Index Term-Uncontrolled  

Ferroelectrics

Index Term-Uncontrolled  

Fluorescence spectroscopy

Index Term-Uncontrolled  

Quantum dots

Added Entry-Corporate Name  

University of California, Berkeley Chemistry

Host Item Entry  

Dissertations Abstracts International. 86-03B.

Electronic Location and Access  

로그인을 한후 보실 수 있는 자료입니다.

Control Number  

joongbu:657168