Film Thickness Dependence of Electrical Properties for Pb(Zr,Ti)O_3 Thin Films Prepared on (111)Ir/TiO_2/SiO_2/Si and (111)Pt/TiO_2/SiO_2/Si Substrates by pulsed-Metalorganic Chemical Vapor Deposition

摘要

Polycrystalline Pb(Zr,Ti)O_3 (PZT) films with various film thicknesses were deposited on (111)Ir/TiO_2/SiO_2/Si and (111)Pt/TiO_2/SiO_2/Si substrates at 540 deg C by source-gas-pulsed metalorganic chemical vapor deposition (pulsed-MOCVD). PZT films deposited on (111)Ir/TiO_2/SiO_2/Si substrates showed good surface flatness and lower leakage current density. The rate of the decrease of remanent polarization (Pr) and the rate of increase of coercive field (Er) for the films with decreasing the film thickness smaller on (111)Ir/TiO_2/SiO_2/Si substrates than those of (111)Pt/TiO_2/SiO_2/Si substrates. In addition, P_r and E_c values saturated at low voltage when the film thickness was the same. As a result, good ferroelectricity with P_r and E_c values of 40 mu C/cm~2 and 140 kV/cm were obtained for 35 nm-thick films prepared on (111)Ir/TiO_2/SiO_2/Si substrates by pulsed-MOCVD.