Type of Document	Dissertation
Author	Wang, Xu
Author's Email Address	xuwang72@yahoo.com
URN	etd-11232004-023529
Title	Pulsed Laser Deposition Growth and Property Studies of Ca2-Xlaxruo4 and Ruo2 Thin Films
Degree	Doctor of Philosophy
Department	Electrical and Computer Engineering, Department of
Advisory Committee	Advisor Name Title Jim P. Zheng Committee Chair Yan Xin Committee Co-Chair Justin Schwartz Committee Member Reginald J. Perry Committee Member Simon Y. Foo Committee Member
Keywords	Calcium Ruthenate Ruthenium Oxide Thin Film Pulsed Laser Deposition
Date of Defense	2004-11-18
Availability	unrestricted
Abstract The newly discovered bulk Ca2RuO4 is an antiferromagnetic Mott insulator with the metal-insulator transition above room temperature and Neel temperature at 113 K. There is a strong coupling between crystal structures and electronic phase transitions in this system, and it exhibits high sensitivity to chemical doping and pressure. The richness of the physical properties and the potential applications of this system motivated us to fabricate thin films of this material, which has never been achieved before. We have epitaxially grown Ca2RuO4 and La doped Ca2-xLaxRuO4 thin films by the pulsed laser deposition technique successfully. Growth conditions such as growth temperature window, target composition, substrates, O2 pressure and O2 flow during growth were systematically studied in order to achieve high quality single-phase films. Crystalline quality and orientation of these films were characterized by x-ray diffractometry and the microstructure was examined by transmission electron microscopy. The electronic transport and magnetic properties were measured and compared with those of bulk single crystals, and the Volmer-Weber island growth mode for the film on LaAlO3 substrate was revealed by atomic force microscopy results. The thin films of rutile structure RuO2, which already has many industrial applications, were grown on (001) LaAlO3 utilizing pulsed laser deposition. Atomic force microscopy was employed to observe the topography at different growth stages, while in situ resistivity measurement was used to monitor the resistance change during and after growth. The changes of resistivity were associated with the change of film growth mode. Transmission electron microscopy was utilized to reveal film quality and crystalline information. The layer-plus-island Stranski-Krastanov growth mode is proposed according to the above results. The ambient O2 filled during growth is found to be the main oxygen source for the oxygen in RuO2 thin film.
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