| Title |
Ferroelectric Properties of Bi4Ti3O12 Thin Films Deposited on Si and SrTiO3 Substrates According to Crystal Structure and Orientation |
| DOI |
http://doi.org/10.5370/KIEE.2018.67.4.543 |
| Keywords |
Ferroelectric oxide ; Bi4Ti3O12 ; Pulsed laser deposition ; Remanent polarization ; Coercive field |
| Abstract |
Ferroelectric Bi4Ti3O12 films were deposited on SrTiO3(100) and Si(100) substrate by using conductive SrRuO3 films as underlayer, and their ferroelectric and electrical properties were investigated depending on crystal structure and orientation. C-axis oriented Bi4Ti3O12 films were grown on well lattice-matched pseudo-cubic SrRuO3 films deposited on SrTiO3(100) substrate, while random-oriented polycrystalline Bi4Ti3O12 films were grown on SrRuO3 films deposited on Si(100) substrate. The random-oriented polycrystalline film showed a good ferroelectric hysteresis property with remanent polarization (Pr) of 9.4 μC/cm2 and coercive field (Ec) of 84.9kV/cm, while the c-axis oriented film showed Pr=0.64μC/cm2 and Ec=47kV/cm in polarizaion vs electric field curve. The c-axis oriented Bi4Ti3O12 film showed a dielectric constant of about 150 and lower thickness dependence in dielectric constant compared to the random-oriented film. Furthermore, the c-axis oriented Bi4Ti3O12 film showed leakage current lower than that of the polycrystalline film. The difference of ferroelectric properties in two films was explained from the viewpoint of depolarization effect due to orientation of spontaneous polarization and layered crystal structure of bismuth-base ferroelectric oxide. |