Strong oxygen pressure dependence of ferroelectricity in BaTiO3/SrRuO3/SrTiO3 epitaxial heterostructures

Abstract

The oxygen pressure effect on the structural and ferroelectric properties have been studied in epitaxial BaTiO3 (BTO)/SrRuO3/SrTiO3 (001) heterostructures grown by pulsed laser deposition. It is found that oxygen pressure is a sensitive parameter, which can influence the characteristics of oxide films in many aspects. The out-of-plane lattice parameter, tetragonality, (c/a) and Ti/Ba ratio monotonously decrease as the oxygen pressure increases from 5 mTorr to 200 mTorr. Microstructural study shows that the growth of BaTiO3 varies from a dense large grained structure with a smooth surface to a small columnar grain structure with rough surface as the deposition pressure increases. Electrical measurements show that the 40 mTorr deposited BTO films present maximum remanent polarization (Pr) (14 μC/cm2) and saturation polarization (Ps) (27 μC/cm2) due to the stoichiometric cation ratio, very smooth surface, and low leakage current. These results demonstrate that the controlling of cation stoichiometry, surface morphology, and leakage current by oxygen pressure is one of very important prerequisites for device applications in the BaTiO3 films.

Microstructure tuning and magnetism switching of ferroelectric barium titanate

“…As it can be noticed, the polarization reversal shows a clear memory and well-saturation indicating the neglectable leakage current in the sample at RT. Remnant polarization (P r ) and saturation polarization (P s ) values of BTO-2 are 4.9 μC/cm 2 and 24.8 μC/cm 2 , respectively, with the applied voltage of 40 V. This is better than many other reports of BTO crystals [18][19][20], but, inferior to that (P r = 14 μC/cm 2 , P s = 27 μC/cm 2 ) previously reported for BTO material deposited on SRO/STO (001) [21], most likely due to microscopic structural variations and/or domain pinning by defects. In addition, the hysteresis loops are shifted slightly in the negative voltage direction.…”

Ferroelectric and piezoelectric responses of (110) and (001)-oriented epitaxial Pb(Zr 0.52 Ti 0.48 )O 3 thin films on all-oxide layers buffered silicon

“…Several studies show that the growth of ferroelectric devices in the form of epitaxial thin films can be performed on both single-crystals (such as SrTiO 3 , LaAlO 3 and MgO) and Si substrates with different conducting perovskite layers as the bottom-electrode . Among the perovskite materials, SrRuO 3 (SRO) and LaNiO 3 (LNO) are not only promising candidates for electrode materials in electroceramic-based devices [22][23][24] due to their good conductivity, but also good candidates for the epitaxial growth of ferroelectric PZT thin films [25,26]. Moreover, these electrodes have also attracted great attention in recent years due to their ability to drastically improve the ferroelectric fatigue properties of the ferroelectric films, as compared to the conventionally used Pt electrodes [27][28][29].…”

Magnetic-control-electric and reversal behavior of ZnO/NiFe/ZnO multilayer films

“…The similar result has been observed in the BaTiO 3 /SrTiO 3 superlattice structure, which was fabricated on SrTiO 3 (001) single-crystal substrate and abnormally enhanced its dielectric property. 21 This explains why the ZnO/NiFe/ZnO multilayer films exhibit a higher dielectric constant compared with that of single ZnO film due to the stress modification by addition of a single NiFe inserting layer. On the other hand, this kind of internal stress relaxation not only enhanced dielectric property but also induced the grain size growth.…”