Control of Crystal Orientations and Its Electrical Properties of PZT/Ru and PZT/RuO_2 Thin Films by MOCVD

摘要

Ru and RuO_2 thin films were deposited on (100)LaAlO_3 (LAO), (100)MgO and (111)Pt/Ir/ SiO_2/Si substrates by MOCVD. Pb(Zr,Ti)O_3 (PZT) was fabricated on Ru/LAO and RuO_2/LAO. Ru thin films deposited at 400℃ or higher on LaAlO_3 and MgO showed epitaxial (001) crystal orientation. (001) uniaxial Ru was deposited on Pt/Ir/SiO_2/Si. RuO_2 thin films with (100) orientation were deposited both on LaAlO_3 and Pt/Ir/SiO_2/Si. (110)-oriented RuO_2 thin film was deposited on MgO. Epitaxial RuO_2 thin films were deposited on LaAlO_3 and MgO at 400℃ or higher. The smoothest surfaces and the lowest room-temperature electrical resistivities were obtained at 400℃ and 450℃, respectively. The crystal orientations and electrical properties of the PZT thin films deposited on the Ru and RuO_2 thin films at 550℃ were strongly affected by the crystal orientations and microstructure of the Ru and the RuO_2 films. Rhombohedral Pb(Zr_(0.6)Ti_(0.4))0_3 thin films deposited on RuO_2/LAO and Ru/LAO at 550℃ with lower growth rate (1.2nm/min) showed (110) and (001) orientation, respectively. The remanent polarization value (Pr) for (001) PZT on Ru/LAO was ～70 μC/cm~2. (110) PZT on RuO_2/LAO showed lower Pr (～30 μC/cm~2), but showed low leakage current (10~(-9) A/cm~2 at 500kV/cm). The dense microstructures and smooth surface structures brought the good leakage characteristics.