Ba0.7Sr0.3TiO3 (BST) single and quadruple layer capacitors with Pt electrodes were fabricated together on polycrystalline alumina substrates with a SiO2-based multicomponent amorphous buffer layer (SiO2/Al2O3). This paper presents the results of the characterization of these capacitors, to demonstrate their suitability for application as decoupling (high value) capacitors and as components in tunable RF applications (e.g., phase shifters and filters). BST films of different compositions, (Ba0.7Sr0.3)TiO3 and (Ba0.5Sr0.5)TiO3, were grown by metal-organic decomposition (MOD) and RF magnetron reactive sputtering. The capacitance density of 90–140 nm thick BST films was in the range of 20 to 70 fF/μm 2. Parallel plate capacitors with areas from 16 μm2 to 2.25 mm2 were fabricated using photolithography and ion milling techniques. For large capacitors (0.125 to 2.25 mm2), capacitance and tanδ were measured at low frequencies (1 KHz - 1 MHz) using an LCR meter. Smaller capacitors (16 μm2 to 3600 μm2) were additionally characterized in the frequency range of 50 MHz - 20 GHz. In such case, capacitance, tanδ and equivalent series resistance (ESR) were extracted from two port scattering parameters obtained using a vector network analyzer (VNA). The relationship between dielectric loss, tunability and calculated figure of merit vs. BST composition and deposition temperature was outlined. In addition, loss and ESR at high frequencies was investigated. The typical achieved leakage current density of sputtered BST films for 2.25 mm2 capacitors fabricated on SiO2/Al2O3 was 7.3×10-9 A/cm2 at 300 kV/cm (65 fF/μm2), about 2 times lower than for (Ba0.7Sr0.3)TiO3 films deposited by MOD (1.4×10-8 A/cm2 at 300 kV/cm, 34.5 fF/μm2). Furthermore, the tunability of (Ba0.7Sr0.3)TiO3 deposited by both methods on SiO2/Al2O3 was ∼60% at 350 kV/cm.

Ferroelectric thin films of BaZrxTi1-xO3 (BZT) were deposited on platinum (Pt) and platinized silicon (Pt/Si) substrates by sol-gel and pulse laser deposition technique respectively. The structure and preferred orientation of the films were examined by x-ray diffraction measurements. The phase formation of sol-gel derived BZT films were found to be at high temperature (1100°C) compare to the pulse laser deposited BZT films ∼ 700°C. Polycrystalline films were observed by both techniques. Ferroelectric nature of the films was confirmed by hysteresis and capacitance-voltage characteristics using platinum top electrodes. Dielectric constant as well as loss was found to decrease by increasing Zr contents. Surface morphology predicted smooth crack free surface.

We have fabricated and characterized Pt (60nm) / (Sr,Sm)0.8Bi2.2Ta2O9 (SSBT, 130nm) / Pt (60nm) / Ti (10nm) / SiO2 (10nm) / p-Si (MFMIS:metal-ferroelectric-metal-insulator-semiconductor) structure FETs. The area ratio, the ratio of SSBT capacitor area to SiO2 capacitor, is varied from 1 to 15 in the MFMIS-FETs. It is demonstrated that MFMIS-FETs with area ratio of 6 have memory window of 0.5V with supply voltage of 5 V. Dependence of memory window on the area ratio is discussed.

Epitaxial Ba0.6Sr0.4TiO3 films were grown onto (001) LaAlO3 by pulsed-laser deposition, and the dislocation structures of the films were investigated using transmission electron microscopy. Misfit dislocations with a periodicity of about 7 nm and Burgers vectors b = a<100> were observed at the interface. High densities of threading dislocations was present in the films with Burgers vector b = a<100>. The observations reveal that threading dislocations are not generated as the result of half-loop climb from the deposit surface as proposed previously, but are instead formed when misfit dislocations are forced away from the interface during island coalescence.

A novel growth mode for hydrothermal films of lead zirconate titanate (PZT) has been discovered. Previously reported hydrothermal PZT films have had a loosely-packed cubic morphology, and indeed that is the most common growth mode. However, under special growth conditions, with much more dilute reagent concentrations than previously reported, substantially vertically oriented, long rod shaped grains may be grown. Metal-organic reagents such as lead acetate trihydrate, zirconium propoxide, and titanium isopropoxide were used along with potassium hydroxide mineralizer. Metal and metal-coated substrates with appropriate perovskite seed layers, such as lead titanate (PT) and PZT were used. Unlike other film deposition methods, such as sputtering, MOCVD, or sol-gel, which typically require greater than 500°C processing temperatures, the hydrothermal processes described in this report allowed the growth of highly crystalline films at temperatures as low as 120°C. The unique vertical rod-like ferroelectric films may be useful in electrical devices such as capacitors.

This paper examines the problem of evaluating the microwave properties of thin ferroelectric films patterned as planar capacitors. Two types of microwave measurements of ferroelectric thin films are considered: reflection and resonance type measurements. Algorithms are presented for evaluation of capacitance-permittivity and dielectric loss. Using sensitivity analysis, the error and limitations associated with these measurements are estimated. The end result is a series of formulae that use the network analyser's measurement data to calculate the capacitance-permittivity, the dielectric loss, and the associated error.

A series of bismuth layer-structured ferroelectrics thin films Srm-3Bi4TimO3m+3(m=3, 4, 5, and 6) were deposited by pulsed laser deposition (PLD) on (001) LaAlO3 single crystal substrate. XRD and Raman studies have been performed. The more sensitive Raman spectra lead to a different understanding on the layer structure of Sr3Bi4Ti6O21 from XRD. This can be attributed to the lager c-axis constant of Sr3Bi4Ti6O21 due to more layers. More layers lead to increasing disorder in the local scale of the average grain.

Hydrothermal method has various advantages; low deposition temperature, high-purity, deposition on a three-dimensional structure and a large thickness. Although epitaxial PZT thin film deposition has reported, ferroelectric measurement has not been conducted due to the peel-off morphology of the film. The present paper investigates the improvement of an epitaxial PZT thin film deposited via a hydrothermal method. By adjusting the position at which the substrate was suspended in the solution, smooth morphology surface was successfully obtained. As a bottom electrode, 200 nm SrRuO3 thin film was deposited on SrTiO3 single crystals, and the PZT thin was deposited on SrRuO3. The remanent polarization 2Pr for PZT on SrRuO3/SrTiO3 (001) was 19.5 μC/cm2 and that of PZT on SrRuO3/SrTiO3 (111) was 37.2 μC/cm2 respectively. The self alignment poling direction was confirmed via scanning nonlinear dielectric microscopy and is thought to have been related to the deposition mechanisms.

Compositionally asymmetric tri-color superlattices (TCS) with a combination of BaTiO3/SrTiO3/CaTiO3 have been grown by pulsed laser deposition (PLD) on atomically-flat SrRuO3-covered (001) SrTiO3 substrates. Conducting SrRuO3 films with single-terrace steps that closely mimic those of the SrTiO3 substrate also were grown by PLD and serve as bottom electrodes. In order to achieve atomic control of each layer, we have calibrated precisely the number of laser pulses required to grow one unit-cell-thick layers (∼200 for a laser spot of 0.4 mm2). These conditions allowed recording of pronounced oscillations of the reflection high-energy electron diffraction (RHEED) specular spot intensity over the entire growth run - even for TCS layers totaling more than 1000 nm in total thickness.

We have measured the dielectric and optical properties of pulsed laser deposited SrBi2Ta 2O9 and Sr0.8Bi2.2Ta2O9 thin films on MgO substrate in THz frequency region by THz time-domain spectroscopy. The imaginary parts of the dielectric constant of both the samples show broad peaks in the frequency range 0.5–1.0 THz, which may be due to the soft mode in SBT in this frequency spectrum. The difference in the real part of the dielectric constant of Sr0.8Bi2.2Ta2O9 thin films is small for MHz and THz frequencies. On the other hand, the value of real part of dielectric constant of SrBi2Ta2O9 thin films in THz frequency range is much smaller than that in MHz frequency region, indicating that SrBi2Ta2O9 is not simply displacive ferroelectric material.

Films of SrBi2Ta2O9 (SBT) were grown on Pt/TiO2/SiO2/Si substrates by the pulsed laser deposition (PLD) technique. The deposits were made at temperatures between 570°C and 715°C, and post-annealed at 750°C. The films grown at 610°C show a (115) preferentially orientation with a small peaks associated to (00l) planes. At higher deposition temperatures, the (00l) peaks increase their intensity, a tendency that is intensified after the heat treatment at 750°C. However, when the films grown at 590–610°C are heat-treated at 750°C, there is a reduction of the crystallites oriented in the (00l) direction, leading to an enhancement of the polarization, reflected in the maximum value of 2Pr = 9.1 μC/cm2 and a coercive field, Ec, of 52.0 KV/cm.

Microstructure studies of ultra-thin BaTiO3 thin films (2–10nm thick) show nano-domains having a width as small as one unit cell. Only 180° nano-domains and 90° domain-boundaries are formed in multi-domains structures. The domain-boundaries are formed at {111} twin boundaries. Most of the domains are oriented in parallel to the film plane but out-of-plane domains are also observed. The films exhibit ferroelectric behavior characterized by a polarization hysteresis loop. A remanent polarization of 3nC/cm2, coercive field of 0.7MV/cm were measured in vertical to the film plane. Temperature-dependent polarization measurements show two peaks of the dielectric constant at about 70°C and 110° C. These peaks are attributed to two Curie temperatures associated with the out-of plane and in-plane domain's orientation, respectively. The switching response of the nano-domains is relatively fast in the range of few nano seconds. The switching time decreases with increasing the applied electric field according to a power law dependence.

The recent demonstration of large ferroelectric memory in rare earth substituted Bi4Ti3O12 attracted a lot of research interest in this material. Bi4-xLaxTi3O12 was synthesized by sol-gel route for different compositions: x = 0.00, 0.46, 0.56, 0.75, 0.95 and thin films were deposited by spin coating on Pt (Pt/TiO2/SiO2/Si) substrate. The post annealed films at 700°C were studied for their structural studies using x-ray diffraction and Raman spectroscopy. The prominent effect of La substitution is observed in low frequency Raman modes. X-ray diffraction and Raman studies show that the film growth was c-axis suppressed. Using improved contacts to Pt substrate, ferroelectric polarization Pr = 51 μC/cm2 has been achieved for 0.63 μm thick film of composition: x = 0.56 (BLT56) without appreciable fatigue.

The use of pyroelectric thin films in uncooled IR detectors has many advantages over the present IR detector technology, which requires extensive cooling for operation. These advantages include reduced weight, reduced footprint, reduced complexity, increased reliability, and decreased maintenance. Ba1-xSrxTiO3 (BST), based thin films are ideal candidates for use in these devices due to their tailorable materials properties. These properties include a high dielectric constant, low dielectric loss, high electrical resistivity, as well as a high pyroelectric constant. BST thin films were doped with Mg in varying amounts, from 0 to 20mol%. The thin films were deposited via metalorganic solution deposition (MOSD) on Pt/Ti/SiO2/Si substrates. Annealing temperatures ranged from 500 to 750 °C. The films were characterized for structural, microstructural, compositional, surface morphological, dielectric and insulating properties. Glancing angle x-ray diffraction (GAXRD) was used to determine crystallinity, phase formation and film orientation. Field emission scanning electron microscopy (FESEM) and cross sectional transmission electron microscopy (TEM) were employed to access surface morphology and microstructure. The Materials Detectivity Figure of Merit (FOM), D*, [D*=pi/(CV(ε0εrtanδ)1/2] was used to evaluate the film's detectivity response. Our results show that undoped Ba60Sr40TiO3, with a value D*= 0.08 (cm3/J)1/2, appears to out perform Pb based pyroelectric thin films, thus making it a viable candidate for IR pyroelectric detector applications.

A comparative study of microstructure and electrical properties of BaxSr1-xTiO3 films made by single- and multi-target pulsed laser deposition was carried out. The films were epitaxially grown on both LaAlO3 and MgO substrates. The structural properties of all samples were investigated using X-ray diffraction and Raman spectroscopy. The elemental composition of the samples was investigated using energy dispersive X-ray analysis. For electrical properties examination, a simple capacitor structure was patterned on the film surface. Thin films made using both methods exhibit similar structural and electrical properties; however the samples made by a multi-target method underwent phase transition in a broader temperature region. The results prove the possibility of using the multi-target pulse laser deposition as a more flexible method for engineering thin film stoichometry.

Epitaxial thin ferroelectric films of Pb(Zr0.53Ti0.47) (PZT) were successfully grown on Sr(Nb)TiO3 (SNTO) single crystal substrates by high-pressure rf sputtering. Pure O2 was used as working gas at a pressure above 1 Torr. Deposition temperature was varied from 550°C to 600°C. Under these conditions we were able to deposit films at a rate of 2.7 Å/min. Their crystalline properties, evaluated by Θ/2Θ, ω and φ scans, showed both in-plane and out of plane orientation. Film composition and film-substrate interface characteristics were studied by Rutherford Backscattering Spectroscopy (RBS). For RBS data the composition ratios for the films were calculated having obtained the expected values for a stoichiometric composition. A very thin diffusion layer of Pb at the film-substrate interface was also introduced. However, the deficiency in Pb, which is correlated to the presence of oxygen vacancies, is lower in our films produced at high O2 pressure than those reported for films produced by sputtering at lower pressures. The ferroelectric hysteresis loops measured in the Pt/PZT/SNTO heterostructures show good ferroelectric behavior with remanent polarizations of 12μ Ccm-2 and coercive field of 50kVcm-1 at 5V. The high-pressured technique representing a useful and capable method capable of obtaining in situ epitaxial, fully oxygenated, pyrochlore-free ferroelectric thin film with high quality structural, compositional and dielectric properties, without post deposit treatment.

(Ba,Sr)TiO3 (BST) films were deposited by RF magnetron sputtering using BST sintered ceramic targets and an approach to deposit BST films with higher permittivity by sputtering deposition was explored aiming to the application of thin film capacitor, RF tunable components and so on.

Basic sputtering conditions such as RF power, deposition temperature and so on were varied in this study. BST films and Pt/BST/Pt capacitors were investigated by electrical properties, XRD analysis and SEM observation. It became clear that deposition temperature, deposition rate, and BST film thickness were important parameters for optimization of the dielectric constant. From the non-linearly relationship between dielectric constant and BST film thickness, we could also find that the interfacial layer between BST and Pt bottom electrode was important for controlling the BST film properties. Furthermore, an approach to enhance the crystalline quality has to be explored for further improvement of BST film properties. Dielectric constant could be raised up to 10% by just changing the gas flow sequence of BST sputtering process.

Pb(ZrxTi1-x)O3 (PZT) thin films with the various Zr/(Zr+Ti) ratios and the film thickness of 50 and 250 nm were epitaxiallly grown on (100)cSrRuO3//(100)SrTiO3 substrates by metalorganic chemical vapor deposition at 540 °C. 50 nm-thick tetragonal PZT films consistd of 100% c-axis-orientation for the Zr/(Zr+Ti) ratio ranging from 0.13 to 0.56, while 250 nm-thick tetragonal ones consistd of about 70% c-axis-orientation for the range from 0.19 to 0.45. On the other hand, 50 and 250 nm-thick films composed rhombohedral single phase for the Zr/(Zr+Ti) ratio above 0.56 and 0.60, respectively. Mixture region of tetragonal and rhombohedral phases was observed from 0.45 to 0.60 for 250 nm-thick films, but was not for 50 nm-thick ones. Remanent polarization monotonously decreased with increasing the Zr/(Zr+Ti) ratio for 50 nm-thick films in tetragonal PZT films. These results show that Ti rich tetragonal PZT thin films have large spontaneous polarization with good square-shape hysteresis loops and are applicable for the high-density capacitor-type ferroelectric random access memories.

Single-crystalline, single-c-domain Pb(Zr0.52Ti0.48)O3 nanoislands (truncated-pyramid in shape) with an average height of ∼9 nm and a base length of ∼50 nm were grown on compressive niobium-doped SrTiO3(001) substrates using chemical solution deposition. Cross-sectional highresolution electron microscopy investigations allowed to propose a growth model of the islands, and they proved the existence of edge-type misfit dislocations at the interface.

The effect of thin Ti/PbZr0.4Ti0.6O3 seed layers on the properties of PbZr0.4Ti0.6O3 (PZT) capacitors has been investigated. The seed layer is based on a bi-layer of thin Ti and thin PZT with a total thickness ranging from 10 to 25 nm, which was deposited on Ir/Pt or Ir/IrO2/Pt by sputtering. After crystallization of the seed layers the main 130-nm-thick PZT film was deposited and crystallized. As a result, a highly preferred (111)-orientation of the PZT was obtained on a 10-nm-thick seed layer, where the peak intensity ratios of (111)/{100} and (111)/{110} are about 100 and 20, respectively. The 10-nm-thick seed forms a pyrochlore phase with a very smooth surface, where the formation of the pyrochlore phase is attributed to Pb diffusion, resulting in a Pb deficient stoichiometry. The seed layer transformed to the perovskite phase during the main PZT crystallization. It is shown that an IrO2 layer beneath the Pt can prevent Pt layer degradation related to the volume expansion due to the oxidation of Ir during the main PZT crystallization. Capacitors with the 10-nm-thick seed layer fabricated on the Ir/Pt and Ir/IrO2/Pt substrates showed typical 2 Pr values of 44.0 μC/cm2 and 41.2 μC/cm2, respectively. The voltage found for 90%-polarization saturation is about 3.0 V, and the capacitors are fatigue-free at least up to 1010 switching cycles.