The ferroelectric and antiferroelectric displacements in perovskite-based ceramics give rise to a wide range of domain structures. This paper reports on transmission electron microscopy observations as a function of temperature of such structures in PLZT and PLSnZT. In the PLZT system superposition of the diffraction patterns from modulated domains of low symmetry give rise to patterns with an apparent high symmetry. The ½(hkl)-type reflections become more intense with decreasing temperature and split into diffuse rods at high temperature. In the PLSnZT system a hierarchy of domain structures is observed with length scales ranging from unit cell dimensions to the full grain size. A temperature dependent long-period modulation along the < 110 > directions is observed.

Photoluminescence (PL) excited at 1.7K with a N2-Laser (3.679eV) was used to investigate defect related electron-hole recombination transitions in ferroelectric PZT thin films. The interaction of doping, heat treatment, and hydrogen with the defect related PL spectrum has been studied. Donor/acceptor related transitions between 3.0 and 3.5eV and deep trap transitions between 2.0 and 2.6eV have been found. Certain heat treatments produce high densities of deep trap transitions in Pb(Zr0.48Ti0.52)03 thin films but not in 6% La doped PZT; different treatments are neccessary to produce similar deep trap transitions in the doped films. Hydrogen anneals eliminate the strongest deep trap transition at 2.15eV in both undoped and La-doped PZT films; however the donor/acceptor transitions are affected differently. Correlation with electrical properties seems to indicate the expected result: smaller defect densities are associated with better electrical performance.

Optical properties were investigated for undoped, La-doped, and Nd-doped Pb(ZrxTi1-x)O3 thin films deposited on sapphire substrates by metalorganic decomposition (MOD) process. Refractive index and extinction coefficient of these films were calculated from transmission spectra in the wavelength range of 300 to 2000 nm. The packing densities of these films were calculated from the refractive index data by using the effective medium approximation. Band gap energies of these films were also reported under the assumption of direct band-to-band transition. The refractive index and band gap energy of PZT films showed a linear dependence on Zr/Ti ratio. The refractive index decreased, while the band gap energy increased with increasing zirconium content. It was also found that both La-doped and Nd-doped PZT films had higher refractive indices than those of undoped PZT films with the same Zr/Ti ratio (50/50).

Polarization-dependent photovoltaic currents are observed in continuously illuminated ferroelectric thin films under conditions of polarization reversal. Following reversal, an initial current rapidly decays to an essentially steady current, which then decays slowly with the current decreasing in proportion to the logarithm of elapsed time. These polarization-dependent currents are attributed to the action of internal fields on photocarriers where the fields result from the incomplete screening of the polarization field.

The crystallization process of PZT thin films has been studied in situ by means of Environmental Scanning Electron Microscopy ( ESEM ). Based on the ESEM observations, the Rapid Thermal Processing (RTP) technique has been employed to crystallize ferroelectric thin films. Various annealing temperature-time combinations were investigated; the results indicate the crystallization process to be very fast. X-ray diffraction data shows the crystallization to be complete in 10 seconds at 600°C, and in 1 second at 700°C. In comparison with conventionally furnace processed films, the RTP films have comparable ferroelectric and dielectric properties, but are distinguished by superior breakdown strengths and morphologically smoother surface. The relation between microstructure of films and crystallizing parameters has been studied.

Thin PZT films 1-4 μm in thickness prepared by sputtering or sol gel methods allow PZT films to be integrated with silicon technology to achieve piezoelectric or pyroelectric structures having small size or mass. Design criteria, materials and processing techniques for such devices are discussed, and the implementation of small size devices on silicon substrates is demonstrated. Factors of importance are the piezoelectric and pyroelectric characteristics achievable in the films, mechanical strength and fatigue, and the stability and compatibility of the films and electrodes with device fabrication procedures and operating conditions.

Thin films of lead zirconate titanate have been fabricated for application to a new family of flexure-wave piezoelectric micromotors that are characterized by low speed and high torque. The high relative dielectric constant and breakdown strength of the films lead to high stored energy densities. Evaluation of the film as a bimorph yielded a value of -88 pC/N for the transverse piezoelectric strain coefficient, d31; the relevant electromechanical coupling factor, k31, calculated thereupon was 0.22. The development of the piezoelectric ultrasonic micromotors from the PZT thin films, and the architecture of the stator structure are described. Nonoptimized prototype micromotors show rotational velocities of 100-300 rpm at drives of 3-5 V.

Ferroelectric thin films have been deposited on polycrystalline silicon micromechanical structures to form both physical microsensors and microactuator devices. These devices which include acoustic pressure sensors, infrared detectors, micropositioners, and stepper motors are based on either the piezoelectric or pyroelectric properties of sol-gel Pb(ZrxTi1-x)O3 or PbTiO3 deposited on surface-machined microelectromechanical structures. Several materials, micromachining, process integration, and performance issues are introduced in the description of these devices.

Ferroelectric PbTiO3 and Lanthanum-modified PbTiO3 thin films have been deposited on different substrate surfaces by sol-gel processing. The ferroelectric, dielectric, and pyroelectric properties and their temperature dependences have been investigated. The sol-gel derived thin films were integrated onto a membrane structure fabricated by solid-state surface-micromachining technology. The performance of the resultant devices have been tested as an uncooled infrared detector. The high voltage responsivity and short rise time are attributed to the combination of the pyroelectric film, the underlying polycrystalline silicon layer, and the thermal design of the composite structure. The addition of Lanthanum with a molecular fraction of 3% and 5% has resulted in a lower dielectric loss and a reduced thermal noise.

Thin films of lead scandium tantalate (Pb(Sc½Ta½)03) (PST) have been prepared by a novel modified sol-gel process. The process involves two deposition steps. In the first, layers of amorphous ScTaO4 are deposited by spin coating a solution of metallorganic compounds of scandium and tantalum. A film of lead oxide is then deposited onto the surface using a solution of lead acetate, and the process repeated to obtain thicker films. After firing the composite film, a pale yellow transparent film of PST is obtained. The films are highly orientated and 100% perovskite.

The film's electrical properties have been measured against field and temperature, showing a strong induced pyroelectric response (peak value of 3.8 x 10−3C/m2K), peak permittivities of 4500 and low loss. The figure-ofmerit of these films (11 x 10−5Pa−½) indicates a performance equivalent to conventional bulk ceramic pyroelectric wafers prepared by slicing, lapping and polishing of ceramic blocks.

The photocurrent responses, photo-induced changes in hysteresis behavior, and electrooptic (birefringence) effects of sol-gel derived PZT films have been characterized as part of an effort to evaluate ferroelectric films for image storage and processing applications.

Three subjects are covered in this paper. First, a set of criteria are established to explain how epitaxial growth can be achieved for sol-gel processed ferroelectric thin films. These criteria describe the conversion of amorphous films to epitaxial films. Second, we report the microstructures of ion beam sputtered buffer layers, (100) MgO on (100) Si, and epitaxial bottom electrodes, (100) Pt on (100) MgO and (111) Pt on (0001) A12O3, for the integration of ferroelectric films with various types of substrates. Third, microstructures of the multilayered epitaxial films, (001) YBa2Cu307-δ on (100) KNbO3/(100) MgO and (100) KNbO3 on (100) MgO/(100) Si, are characterized. The results indicate that high quality epitaxial multilayered films can be obtained under the proper processing conditions.

Lanthanum-modified lead-titanate (Pbo.85Lao.1Ti03) thin films were fabricated by rf magnetron sputtering on various kinds of substrates such as single-crystal MgO (100), r-plane sapphire and SI (100) with an MgO thin film layer. All the films were able to be evaluated using nickel alloy electrodes which possess low reactivity with PbO, excellent heat-resistance and oxidation-resistance. The quality of these films was affected by the kind of substrate and crystal orientation of nickel alloy electrode used. Furthermore, by controlling the crystal orientation of the alloy electrode, films on Si (100) with an MgO (100) layer showed good ferroelectricity.

Annealing behavior in oxygen ambients of the of the ferroelectric PZT on Hf and Zr electrodes has been studied in the temperature range of 500-800°C using the 3.045MeV O16(∝,∝)O16 resonance in backscattering spectrometry. Internal oxidation of the buried metal electrode was observed. Oxygen concentration of the PZT film decreases with increasing temperature. Pb loss of the PZT film occurred above 700°C.

A wide range of electrode materials have been investigated for use in ferroelectric-silicon CMOS technology. Numerous metal and metal-oxide films were deposited on silicon substrates and coated with sol-gel derived ferroelectric thin films. The films were sintered in either a diffusion furnace or by rapid thermal processing. Transmission electron microscopy was used to investigate the evolution of the resulting ferroelectric thin film microstructure and ferroelectric / electrode material interactions.

Microstructural differences such as the volume fraction of the ferroelectric perovskite and pyrochlore phase, domains and grain structure are correlated with electrical results. A strong microstructural dependence on the substrate was found for the Cr, Zr, Hf and Ni electrode materials. In general, chromium and other metal-oxide films had high leakage currents and large volume fractions of the non-ferroelectric pyrochlore phase. Nickel electrodes displayed the best electrical results, but the microstructure is very different from the other ferroelectric films.

Sol gel prepared PZT films from 0.3 - 1.0 μm in thickness can be crystallised at temperatures down to 520°C on aluminium substrates, but such films are often non-ferroelectric. Comparison with films made on Pt substrates suggests that reduced oxygen content at the interface nucleates a cubic non-ferroelectric PZT phase.

The deposition of the bottom electrode plays a key role in the fabrication of ferroelectric capacitors. Processing at elevated temperatures of up to 800°C can give rise to diffusion processes and thereof formation of harmful dielectric layers.

In this paper we used Rutherford backscattering spectrometry (RBS), Auger electron spectrometry (AES) and transmission electron microscopy (TEM) to study Pt/Ti/SiO2/Si substrates with various thicknesses of the Ti and Pt layers. During heating up to about 450°C in vacuum the initial layer sequence remains unchanged. However, drastic changes occur when the electrodes are exposed to Ar/O2 atmosphere during heat treatment. Oxidation induced diffusion of Ti into Pt and oxidation of Ti were observed. A Pt electrode with a 100 nm thick Ti adhesion layer proved to be suitable for the "in-situ" deposition of PZT films.

Ferroelectric thin films of PbZr0.5Ti0.5O3 were prepared by sol-gel process. Top electrodes of different sizes were deposited on thin films in order to study their influence on electrical properties. Histograms of the measured electrical characteristics are related to the electrode sizes. By reducing the electrode size, it is possible to improve the electrical properties of the film. Various properties, such as remanent polarization Pr and coercive voltage Vc, were measured statistically in order to show the evolution of their mean value and of their variance with the electrode size.

Polarization dependent conductivity is a dependence of the low field non switching steady state conduction current through a metal ferroelectric metal (MFM) thin film capacitor on the remanent polarization state of the capacitor. This paper proposes a simple theoretical model based on Schottky barrier formation due to PZT-platinum work function differences and barrier height modulation due to remanent polarization. The model predicts a conduction current dependence on both remanent polarization state and electrode material. Finally, we present experimental data in qualitative agreement with the model.

This paper describes a detailed physical analysis of the electric fields, space charges, and polarization of thin-film ferroelectric devices. The analysis is based on a previously developed model of the electric field dependent polarization, permittivity, and hysteresis of the thin-film polycrystalline ferroelectric, which was derived from the Landau-Devonshire theory. This paper includes the macroscopic effects related to device structure and composition, including potential barriers at contacts, domain relaxation, grain boundary surface charge, and interactions between the space charges and the non-linear polar displacement.