Comparison of crystal structure and electrical properties of tetragonal and rhombohedral Pb(Zr,Ti)O_(3) films prepared at low temperature by pulsed-metalorganic chemical vapor deposition

摘要

The crystal structure and the electrical properties were systematically compared for tetragonal and rhombohedral Pb(Zr,Ti)O_(3) PZT films prepared at various deposition temperatures from 580℃ to 395℃ on (111) Pt/Ti/SiO_(2)/Si substrates by pulsed-metalorganic chemical vapor deposition (pulsed MOCVD). Film orientation changed from (111) to (100) and/or (001) with the decrease in the deposition temperature, but the well-crystallized PZT phase was obtained down to 395℃. The lattice parameter was almost constant with decreasing deposition temperature, suggesting that the Zr and Ti elements in the films were incorporated into the PZT phase. When the deposition temperature decreased, the leakage current density decreased together with a decrease in surface roughness, especially for tetragonal PZT films. Remanent polarization (P_(r)) continuously decreased with decreasing deposition temperature down to 395℃, but was above 20 μC/cm~(2) even at 395℃. Specifically, the tetragonal film shows good squareness down to 415℃. These results show that PZT films with low leakage current density and a large P_(r) were obtained even at 395℃ by pulsed MOCVD irrespective of the film composition.