Powered by Indico
v3.2.8
RuO2 is known as a good conducting oxide material. I deposited hetero-epitaxial RuO2 films on C-plane Sapphire(Al2O3) substrates using RF sputtering. In order to find the optimal condition, the RuO2 films were made at various deposition temperatures from 300 °C to 800 °C, and their physical properties such as surface morphology, structural and electrical properties were measured by AFM, XRD and R-T measurement techniques. In addition, the RuO2 films were deposited on various sapphire substrate with different crystal orientations, such as A-plane, C-plane, M-plane, and R-plane. As the deposition temperature increased up to 650 °C, the XRD peak intensity and the surface roughness of the (100) RuO2 film on C-plane showed an increasing tendency and the resistivity decreased as a typical metallic material. When the deposition temperature increased above 700 °C, the properties of RuO2 film became worse. The properties of RuO2 films was dependent on the crystal orientation of substrate. In contrast to the (100) RuO2 on C-plane, the (101) RuO2 film was grown on A-plane and R-plane, and the (001) RuO2 film was made on M-plane.The surface roughness of the RuO2 film was minimum on R-plane and maximum on M-plane, while the FWHM in rocking curve was minimum on C-plane. Although the crystallinity of the RuO2 film along the out-of-plane direction was best on C-plane, the resistivity was relatively large on C-plane. Interestingly, the resistivity of the RuO2 film was minimum on R- plane. In order to investigate the application possibility of the epitaxial RuO2 film as a bottom electrode, I made a trilayer structure Ag/ZnO/RuO2 on Al2O3, which is similar to a typical resistive switching device. The I-V curve of the trilayer showed a large resistance change of about 104 times as the applied voltage increased. Such a resistance change was similar to a typical property of the so-called WORM memory.
Thesis Advisor: Prof. Joonghoe Dho