Ferroelectric bismuth titanate films by hot wall metalorganic chemical vapor deposition
Ferroelectric bismuth titanate thin films were successfully deposited on Si, sapphire disks, and Pt/Ti/SiO2/Si substrates by hot wall metalorganic chemical vapor deposition. Triphenyl bismuth [Bi(C6H5)3] and titanium ethoxide [Ti(C2H5O)4] were used as the precursors. The deposition rates were in the range of 3.9-12.5 nm/min. The Bi/Ti ratio was easily controlled by precursor temperature, carrier gas flow rate, and deposition temperature. As-deposited films were pure Bi4Ti3O12 phase. The films were specular and showed uniform and fine grain size. Optical constants as a function of wavelength, were calculated from the film transmission characteristics in the ultraviolet-visible-near infrared (UV-VIS-NIR) region. The 550-degrees-C annealed film showed a spontaneous polarization of 26.5 muC/cm2 and a coercive field of 244.3 kV/cm.