Preparation of c-Axis Oriented PbTi0₃ Films by MOCVD

Thin films of Pb—Ti—O were prepared on MgO(lOO) substrates by chemical vapor deposition using Pb(C₂H₅)₄ and Ti(OC₃H₇)₄ as sources. When the evaporation temperatures of Pb(C₂H₅)₄ and Ti(OC₃H₇)₄ were 50 and 15°C, respectively, the Pb/Ti molar ratio of the films had a maximum value about 1.2 at 500 °C. The Pb/Ti ratio of the deposits obtained at 600 °C decreased with increasing total gas pressure. The peaks from perovskite-type structure with the tetragonal symmetry were observed in the X-ray diffraction patterns of the films deposited at 2kPa and 400∼800 °C and at 2∼8 kPa and 600 °C, Most of the films shows αpha;-axis and c-axis orientation perpendicular to the film plane. The ratio of c-axis orientation “αpha;” was evaluated by using an equation: αpha; =I(001)/{I(001) +7(100)}, where 1(001) and 7(100) were the X -ray diffraction intensities of (001) and (100) reflection, respectively. The values of αpha; increased when the Pb/Ti molar ratio approached to 1. PbTiO₃ thin films having a high c-axis orientation of αpha; =0.98 were successfully prepared with a deposition rate of 17 nm/min at 500°C.