Pulsed Laser Deposition Growth and Property Studies of Ca₂₋xLaRuo₄ and Ruo₂ Thin Films

• Other Authors: Wang, Xu (authoraut)
• Format: Others
• Language: English; English
• Published: Florida State University
• Subjects: Electrical engineering; Computer engineering
• Online Access: http://purl.flvc.org/fsu/fd/FSU_migr_etd-1267

The newly discovered bulk Ca2 RuO4 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 Ca 2 RuO4 and La doped Ca2-x Lax RuO4 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 LaAlO 3 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 O 2 filled during growth is found to be the main oxygen source for the oxygen in RuO2 thin film. === A Dissertation Submitted to the Department of Electrical and Computer Engineering in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy. === Fall Semester, 2004. === November 18, 2004. === Calcium Ruthenate, Ruthenium Oxide, Thin Film, Pulsed Laser Deposition === Includes bibliographical references. === Jim P. Zheng, Professor Co-Directing Dissertation; Yan Xin, Professor Co-Directing Dissertation; Justin Schwartz, Outside Committee Member; Reginald J. Perry, Committee Member; Simon Y. Foo, Committee Member.