BiFeO3, a material with coexistence of antiferromagnetic and ferroelectric phases at room temperature, has been expecting to be used on novel devices such as FeRAM and spintronics. In this research, it is found that the surface morphologies of SrTiO3 influence the subsequence growth of SrRuO3 and Pb-dopant BiFeO¬3 (PBFO) films. The domain structures are associated to various surface structure and different thickness of PBFO investigated by a piezoresponse force microscopy. The radial-polarization-like domains was found on the PBFO island structures, and the domain size and the remnant piezoresponse increases with the thickness increasing; in contrary, the shifting of the electric coercive field occurs in the thinner films.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

The digital information processing system has benefited tremendously from the invention and development of complementary metal-oxide-semiconductor (CMOS) integrated circuits. The relentless scaling of the physical dimensions of transistors has been consistently delivering improved overall circuit density and performance every technology generation. However, the continuation of this trend is in question for silicon-based transistors when quantum mechanical tunneling becomes more relevant; further scaling in feature sizes can lead to increased leakage current and power dissipation. Numerous research efforts have been implemented to address these scaling challenges, either by aiming to increase the performance at the transistor level or to introduce new functionalities at the circuit level. In the first approach, novel materials and device structures are explored to improve the performance of CMOS transistors, including the use of high-mobility materials (e.g. III-V compounds and germanium) as the channel, and multi-gate structures. On the other hand, the overall circuit capability could be increased if other state variables are exploited in the electronic devices, such as the electron spin degree of freedom (e.g. spintronics). Here we explore the potential of germanium nanowires in both CMOS and beyond-CMOS applications, studying the electronic and spintronic transport in this material system. Germanium is an attractive replacement to silicon as the channel material in CMOS technology, thanks to its lighter effective electron and hole mass. The nanowire structures, directly synthesized using chemical vapor deposition, provide a natural platform for multi-gate structures in which the electrostatic control of the gate is enhanced. We present the realization and scaling properties of germanium-silicon-germanium core-shell nanowire n-type, [omega]-gate field-effect transistors (FETs). By studying the channel length dependence of NW FET characteristics, we conclude that the intrinsic channel resistance is the main limiting factor of the drive current of Ge NW n-FETs. Utilizing the electron spins in semiconductor devices can in principle enhance overall circuit performance and functionalities. Electrical injection of spin-polarized electrons into a semiconductor, large spin diffusion length, and an integration friendly platform are desirable ingredients for spin based-devices. Here we demonstrate lateral spin injection and detection in Ge NWs, by using ferromagnetic metal contacts and tunnel barriers for contact resistance engineering. We map out the contact resistance window for which spin transport is observed, manifestly showing the conductivity matching required for spin injection. / text

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Over the past decade there has been a great deal of interest in graphene, a 2-dimensional allotrope of carbon with exceptional mechanical and electrical properties. Its outstanding mobility, minimal size, and mechanical stability make it an appealing material for use in next generation electronic devices. Epitaxial graphene growth on silicon carbide is a reliable, scalable method for the production of high quality graphene films. Recent work has shown that the SiC can be patterned prior to graphitization, in order to selectively grow graphene nanostructures. Graphene nanoribbons grown using this technique do not suffer from the rough edges caused by lithographic patterning, and recent measurements have revealed extraordinary transport properties. In this thesis the magnetic properties of these nanoribbons are investigated through spin polarized current injection. The sensitivity of these nanoribbons to spin polarized current is interesting from a fundamental physics standpoint, and may find applications in future spintronic devices.

Thesis (Ph.D.)--University of Delaware, 2008. / Principal faculty advisor: John Q. Xiao, Dept. of Physics and Astronomy. Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2008.

Thesis (Ph.D)--Physics, Georgia Institute of Technology, 2008. / Committee Chair: Dragomir Davidovic; Committee Member: Alexei Marchenkov; Committee Member: David Citrin; Committee Member: Elisa Riedo; Committee Member: Walter A. de Heer. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (PH.D.)--Michigan State University. Physics, 2008. / Title from PDF t.p. (viewed on Aug. 11, 2009) Includes bibliographical references (p. 156-164). Also issued in print.