Stoichiometric and Ti-doped LiNbO3 films could be synthesized by the organometallic route. The films were epitaxially crystallized at temperatures around 400°C on sapphire substrates. The reaction control of alkoxides in solvent was found to be very critical for adjusting the stoichiometry and the low temperature crystallization, as well as the crystallization in water vapor stream.

Ferroelectric thin films including undoped and doped PZT (lead zirconate titanate), BaTiO3 (barium titanate), SBN (strontium barium niobate), KNbO3 (potassium niobate), PBN (lead barium niobate), KNSBN (potassium sodium strontium barium niobate), and LiNbO3 (lithium niobate) were made on silicon and fused silica substrates by a sol-gel process. Microstructure and physical (pyroelectric, ferroelectric and optical) properties of these thin films were studied. Transparent and preferentially orientated SBN thin films on fused silica substrates can be obtained by applying a d.c. electric field during heat treatment. A heterojunction effect was observed in ferroelectric thin films on both n-silicon and p-silicon through measurement of I-V characteristics, and by the demonstration of a photocurrent effect.

Thin-layers of lithium niobate were deposited on polycrystalline platinum and (001) sapphire. Preferred orientation was observed by x-ray diffraction measurements, and confirmed by x-ray rocking curve studies. The orientation was [006] LiNbO3 with [111] Pt and [001] Al2O3. Dielectric data are reported for grain oriented LiNbO3 as a function of frequency for layer thicknesses from 0.15 to 0.70 μm.

Thin films (.1-.6 μm) of LiNbO3 have been deposited on silicon substrates by reactive rf sputtering. Under optimized deposition conditions the resulting thin films of LiNbO3 were optically transparent, adhered well to the silicon substrates, and were found to be polycrystalline and uniaxial with the c axis oriented normal to the silicon surface. Optical microscopy and scanning electron microscopy were used to examine film morphology. Both methods indicated that the films were smooth and contained no gross irregularities. The ratio of oxygen to niobium in these films was measured by Rutherford backscattering to be approximately 3 to 1. Auger electron spectroscopy depth profiling revealed that the films had the expected ratio of Li, Nb, and O. This information, together with Bragg x-ray diffraction data, indicates that the thin films deposited on silicon were stoichiometric, crystalline LiNbO3.

Thin films (.1-.6 μm) of LiNbO3 have been deposited on silicon substrates by rf reactive sputtering. MFS (metal-ferroelectric-semiconductor) capacitor structures were created by a liftoff process which physically isolated small areas of LiNbO3. Standard MOS (metal-oxide-semiconductor) electrical characterization techniques were used to determine the resistivity and dielectric constant of the films. Short-circuit photocurrent measurements revealed both transient and steady state components attributed to a pyroelectric effect and a bulk photovoltaic effect respectively. The conduction processes in these films were examined and found to exhibit Frenkel-Poole characteristics. Ferroelectric switching at room temperature has also been observed in these films, however, the reversed orientation was not stable.

There is a growing interest in thin films of ferroelectric oxides because of their electronic and optoelectronic applications. Various growth processes are being explored, but here, we review progress with chemical vapour deposition in a purpose built low pressure reactor. The two ferroelectric perovskites selected for our initial studies were lead titanate and lead scandium tantalate which have necessitated the synthesis of proprietary precursors. These compounds are based on metal alkoxides and β-diketonates, and are suitably modified to exhibit the required volatility and necessary thermal and hydrolytic stabilities.

Deposition has been studied over the temperature range 400–800°C and, in general, amorphous films result which can be converted by subsequent annealing to crystalline perovskites. However, the inclusion of hydroxyl group compounds (H2O or alcohols) in the vapour train catalyses the crystallisation process and enhances the growth rates at temperatures in excess of 600°C. In order to deposit the perovskite phase, it is important to maintain the gas phase composition throughout the growth. Deposition rates of up to 10μm/hour can be achieved, but the best thin films, in terms of density and morphology, are formed at lower deposition rates. The crystallite size of the deposit may vary from 0.1μm up to 2μm, depending on temperature. The choice of precursors, gas compositions and the growth conditions will be discussed in conjunction with the electrical and structural properties of the layers grown.

The feasibility of chemical beam deposition of PbTiO3 thin films is demonstrated. The method utilizes chemical (molecular) beams of metalorganic precursors in a high vacuum chamber. Pyrolysis reactions of the metalorganics at the substrate surface are facilitated by presence of active oxygen from an ozone source. Fine grained, smooth polycrystalline PbTiO3 films have been deposited at substrate temperatures as low as 325°C.

Thin film of crystalline barium titanate, BaTiO3, has been prepared from Ti metal at 100–200°C by a new technique called “hydrothermal-electrochemical method” which could be categorized into a variety of the extended hydrothermal method. The reaction was carried out in an electrolytic cell containing 0.1–0.5N Ba(OH)2 aqueous solutions at temperatures of 100–200°C and under saturated vapor pressures. Titanium metal substrate or Ti-deposited glass substrate was used for the anode and a Pt plate for the cathode. Between the electrodes, a constant current density up to 100 mA/cm2 was applied galvanostatically for 10–80 min. Surface of the BaTiO3 film was lustrous and free from any visible defects. Thickness of the BaTiO3 films ranged from 70nm to 300nm. The adhesion between the film and substrate was so strong that no exfoliation was observed. Similar BaTiO3 thin films with thickness less than 70 nm were also formed even in simple hydrothermal conditions without applying any electric current.

An analysis is presented of the ion beam sputter deposition of ferroelectric KNbO3 and Pb(Zr, Ti)O3 (PZT), and the observed compositional, structural, and microstructural properties of these films. Films are deposited using a specially designed computer-controlled system with ability to produce multicomponent films via layer-by-layer deposition of elemental components. Metal or oxide targets are sequentially exposed to a high current ion beam by means of a rotatable target holder. A quartz crystal resonator provides feedback information on layer thicknesses to the computer. Precise control of film stoichiometry is obtained using this method.

KNbO3, a material possessing a high figure-of-merit for electrooptic applications, has been deposited epitaxially on (100) MgO substrates. The structure of the optically transparent films has been studied with x-ray and electron diffraction, and transmission electron microscopy. The effects of various processing parameters on the microstructure of the films are discussed.

We have demonstrated the ability of the technique to produce multicomponent films and control cation concentration at elevated substrate temperatures for materials such as PZT. The microstructure and associated ferroelectric properties are discussed in relation to processing conditions.

The growth of ferroelectric lead zirconate titanate (PZT) films by rf-sputtering using facing targets is described. This study has focused on producing thin (<500 nm) PZT films on a wide range of substrates including magnesium oxide, spinel, alumina, silicon oxide, and the respective substrates coated with platinum. Deposition was from two opposed targets separated by 10–15 cm, with the substrate plane normal to the targets and outside the cylinder defined by the two targets. This geometry was chosen to obtain compositional uniformity and avoid ion bombardment effects. The deposition temperatures ranged from RT to 700 °C and the process gas was a mixture of argon and oxygen. Effects of deposition conditions and post-deposition annealing on film composition, microstructure, and properties were evaluated using Rutherford backscattering spectroscopy (RBS), x-ray diffraction, optical and electron microscopy, and various electrical measurements. Optimization of process conditions is discussed in terms of phase purity, preferred orientation, and minimization of electrode interaction.

Ferroelectric and transparent lead–zirconate–titanate thin films were fabricated by rf sputtering. The substrates used were Pt–coated single crystal silicon. The deposition temperatures were relatively low (≅ 200°C). Annealing at high temperatures yielded first pyrochlore type and finally perovskite with good switching characteristics. The phase structure, microstructure, surface composition, and properties were measured as a function annealing time and temperature. In general, the Pb concentration on the surface decreased with increasing annealing temperature or time, whereas Zr concentration increased. It was observed that the grain size of perovskite PZT did not show any significant changes with increasing either anneal temperature or time.

The deposition of ferroelectric PLZT on r-plane sapphire using R-F Triode Magnetron Sputtering is reported. R-plane (1102) sapphire is chosen, in spite of its large lattice mismatch to PLZT, because of its capability of integrating MOS silicon circuits with PLZT modulators. Perovskite PLZT films with the desired composition (9/65/35) are obtained using co-deposition techniques around 500°C and post deposition annealing at 650°C. The deposited films exhibit good optical and electro-optical properties. The room temperature dielectric constant of the films was 1800 at 10 Khz. The refractive index of the films was in the range 2.2–2.5. The films showed a quadratic E-O effect with R=0.6×10−16 m2/V2. The films are promising for smart Spatial Light Modulators (SLM) applications.

High quality PLZT thin films have been deposited using ion beam sputtering. The deposited material has perovskite crystal structure tetragonal in phase with the c-axis predominantly normal to the surface. Material deposited at temperatures below 450°C has pyrochlore structure while that deposited above 650°C displays polycrystalline characteristics. The deposition rate was approximately 0.2–0.5 Å/sec yielding film thicknesses of ∼4500 Å. The surface morphology of the deposited films is of high quality with a RMS roughness 60% that of magnetron sputtered films.

Thin film process for ferroelectric perovskite oxides has been investigated. Amorphous, polycrystal, and epitaxial thin films of Pb-based perovskite ferroelectrics were prepared by rf-magnetron sputtering, and their properties were discussed. Epitaxial PLZT thin films showed similar dielectric properties as PLZT bulk ceramics and also showed strong electrooptic effect. For further investigation, film preparation process was developed by multitarget sputtering and quaternary PLZT thin film with excellent epitaxial crystallinity was realized by using a graded composition layer.

The synthesis of ferroelectric lead zirconate titanate (PZT) films by pulsed laser deposition at 248 nm is described. This study has focused on producing thin (≲ 0.6μm) PZT films on bare and platinum coated MgO < 100 > substrates. Deposition was in an oxygen gas ambient (30 mTorr) at temperatures typically ∼ 525 °C. Rutherford Backscattering Spectroscopy (RBS) was used to evaluate film composition. Film lead content was found to decrease both with increasing laser fluence, and increasing substrate temperature. Film microstructure was evaluated by x-ray diffraction. Electrical measurements were made on the films before and after annealing to determine the dielectric constant and polarization. Properties after annealing were substantially improved, with dielectric permittivity values comparable to bulk PZT.

The deposition of thin films of ferroelectric materials by the laser ablation technique was investigated. The films were grown by ablation from a bulk target of lead zirconate titanate (PZT) exposed to laser pulses from CO2 amd KrF excimer lasers. The effects of deposition and annealing conditions on the structure and stoichiometry of the films were studied.

Laser ablation provides a suitable technique of ferroelectric thin film deposition. We have used this technique to produce films of Pb1−xLax(Zr1−y Tiy)1−x/4O3 (PLZT), a class of ceramic materials which has a wide range of composition dependent electro-optical properties. PLZT films of (7/0/100) and (28/0/100) composition have been deposited onto both crystalline Si <100> and amorphous fused silica substrates. Laser ablation provides high deposition rates and good crystal structure of thin ferroelectric films on silicon. The methods required to achieve proper stoichiometry in the films are also discussed.

Lead zirconate-titanate (PZT) thin films were prepared by the laser ablation technique. The PZT (Zr/Ti=53/47) target was irradiated using a focused q-switched Nd:YAG laser (15 ns, 100 mJ at 1.064 μ;m). The as-deposited films were amorphous as indicated by X-ray powder patterns, but crystallized readily with brief annealing above 650°C. The dielectric constant and the resistivity of the crystallized films were studied using a parallel-plate type capacitor structure.

A review of the history of ferroelectric (FE) thin film synthesis is given covering the period of the 1960's to the present. Early methods, materials and applications are discussed. An assessment of the recent upsurge in activity takes note of current targeted applications, including nonvolatile memory, piezoelectric actuators, capacitors, and electro-optic devices. Focus is placed on similarities and differences in the most common film deposition processes. Comparison of microstructure and composition variation seen in films deposited by sputtering, laser ablation, and solution deposition is made. More detailed understanding of process-microstructure relations is stressed as necessary for film property control. Also discussed are the roles of substrate interactions and interface layers in thin film growth.

Lead zirconate titanate ferroelectric thin films have been fabricated and fully integrated with standard CMOS semiconductor technology to produce non-volatile IC memory devices, now being tested in the marketplace. Starting with an organo-metallic sol-gel and using standard IC spin-on glass and annealing technologies, perovskite type ferroelectric thin films are formed. A variety of techniques have been under study for characterizing the crystalline microstructumre of the ferroelectric layer. Presented here are observations made with optical and scanning electron microscopy, and X-ray diffraction analysis of the effects of ferroelectric composition and sinter temperatures on crystal structure.