Rao, Yangyan = 氧化鋅的納米結構以及准一維氧化鋅稀磁半導體的合成及研究 / 饒洋燕. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references. / Abstracts in English and Chinese. / Rao, Yangyan = Yang hua xin de na mi jie gou yi ji zhun yi wei yang hua xin xi ci ban dao ti de he cheng ji yan jiu / Rao Yangyan. / Abstract --- p.1 / 摘要 --- p.3 / Acknowledgments --- p.4 / Table of contents --- p.5 / Chapter Chapter 1 --- Introduction --- p.7 / Chapter 1.1 --- Zinc oxide --- p.7 / Chapter 1.2 --- Mn doped ZnO diluted magnetic semiconductors --- p.7 / Chapter 1.3 --- Motivations --- p.9 / Chapter 1.4 --- Our Work --- p.10 / Chapter 1.5 --- Overview of the thesis --- p.11 / References --- p.11 / Chapter Chapter 2 --- Experimental set-up and conditions --- p.15 / Chapter 2.1 --- Chemical Vapor Deposition --- p.15 / Chapter 2.1.1 --- Key Steps in Chemical Vapor Deposition --- p.15 / Chapter 2.2 --- Experiments on the synthesis of ZnO nanostructures --- p.16 / Chapter 2.2.1 --- Set-up --- p.17 / Chapter 2.2.2 --- Growth mechanism --- p.18 / Chapter 2.2.3 --- Experimental conditions --- p.20 / References --- p.23 / Chapter Chapter 3 --- Characterization of pure ZnO --- p.25 / Chapter 3.1 --- Morphology of ZnO nanowires --- p.25 / Chapter 3.2 --- Lattice structure --- p.30 / Chapter 3.3 --- Photoluminescence property (PL) --- p.32 / Chapter 3.4 --- Lattice dynamics´ؤRaman spectra --- p.33 / References --- p.35 / Chapter Chapter 4 --- Properties of Mn doped ZnO nanowires --- p.37 / Chapter 4.1 --- Morphology and composition --- p.37 / Chapter 4.2 --- Lattice structure of Mn-doped ZnO --- p.40 / Chapter 4.3 --- Lattice dynamics´ؤRaman study of Mn-doped ZnO nanowires --- p.46 / References --- p.48 / Chapter Chapter 5 --- Magnetic properties of Mn doped ZnO nanowires --- p.50 / Chapter 5.1 --- Theory of DMS --- p.50 / Chapter 5.2 --- Magnetic results of Mn doped ZnO nanowires --- p.52 / Chapter 5.2.1 --- Paramagnetism of Mn doped ZnO --- p.52 / Chapter 5.2.2 --- Ferromagnetism of Mn doped ZnO --- p.58 / References --- p.65 / Chapter Chapter 6 --- Conclusions --- p.67

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 163-175).

New semiconductor materials may enable next-generation â spintronicâ devices which exploit both the spin and charge of an electron for data processing, storage, and transfer. The realization of such devices would benefit greatly from room temperature ferromagnetic dilute magnetic semiconductors. Theoretical predictions have suggested that room temperature ferromagnetism may be possible in the wide bandgap semiconductors GaMnN and ZnMnO, though the existing models require input from the growth of high-quality materials. This work focuses on an experimental effort to develop high-quality materials in both of these wide bandgap materials systems. ZnMnO and ZnCoO single crystals have been grown by a modified melt growth technique. X-ray diffraction was used to examine the structural quality and demonstrate the single crystal character of these devices. Substitutional transition metal incorporation has been verified by optical transmission and electron paramagnetic resonance measurements. No indications of ferromagnetic hysteresis are observed from the bulk single crystal samples, and temperature dependent magnetization studies demonstrate a dominant antiferromagnetic exchange interaction. Efforts to introduce ferromagnetic ordering were only successful through processing techniques which significantly degraded the material quality. GaMnN thin films were grown by metalorganic chemical vapor deposition. Good crystalline quality and a consistent growth mode with Mn incorporation were verified by several independent characterization techniques. Substitutional incorporation of Mn on the Ga lattice site was confirmed by electron paramagnetic resonance. Mn acted as a deep acceptor in GaN. Nevertheless, ferromagnetic hysteresis was observed in the GaMnN films. The apparent strength of the magnetization correlated with the relative ratio of trivalent to divalent Mn. Valence state control through codoping with additional donors such as silicon was observed. Additional studies on GaFeN also showed a magnetic hysteresis. A comparison with implanted samples showed that the common origin to the apparent strong ferromagnetic hysteresis related to contribution from Mn substitutional ions. The observed magnetic hysteresis is due to the formation of Mn-rich regions during the growth process. This work demonstrated that the original intrinsic models for room temperature ferromagnetism in the wide bandgap semiconductors do not hold and the room temperature ferromagnetism in these materials results from extrinsic contributions.

The present work is mostly focused on theoretical study of multiferroics and magnetic semiconductors within the framework of density functional theory (DFT). We studied Bi₂NiMnO₆ which was recently synthesized as a heavily distorted double perovskite with four formula units in a monoclinic unit cell. The calculated GGA and GGA+U magnetizations per formula unit were 4.92 and 4.99 [mu]B and the calculated ferroelectric polarizations were 16.83 and 16.63 [mu]C cm⁻². We also present the results of completely relaxed electronic structure calculations for multiferroic LaMnO₃/BaTiO₃ structure which was built by joining a slab of magnetic LaMnO₃ with a slab of ferroelectric BaTiO₃. The study of Mn doped GeTe, which is a diluted magnetic semiconductor (DMS), shows the net magnetization as a function of doping and holes concentration. In addition, we present a study of ferroelectric GeTe as a function of applied pressure and the interesting properties exhibited by Si(001)/Si(110) junction which was experimentally built using hybrid orientation technology (HOT).

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 102-108). Also available on the World Wide Web.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 63-66). Also available in electronic version. Access restricted to campus users.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 155-170).

Thesis (Ph. D.)--Florida State University, 2004. / Advisor: Dr. Elbio Dagotto, Florida State University, College of Arts and Sciences, Dept. of Physics. Title and description from dissertation home page (viewed Sept. 21, 2004). Includes bibliographical references.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 64-66). Also available in electronic version.