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As the number of passive components in electronic circuits increases, new methods for fabricating passives are under development to optimize utilization of board space. In this paper, we will describe the performance capabilities of TPL's micro‐contact printing (μCP) process to fabricate near‐net‐shape structures with feature sizes ranging from 100 microns to the sub‐micron scale. Like thick film processes, this novel process is compatible with a broad materials base, making a large range of materials properties available. Unlike thick film, however, this novel process employs powder‐free inks that can be patterned with high resolution. It is anticipated that this process will enable integration of passive components that show thin film performance at thick film cost. Emphasis in this paper will be placed on processing conditions, and materials properties to demonstrate the feasibility of this process for passive device fabrication.

The development of stress in the SrBi2Ta2O9 (SBT) films generated from a chemical solution deposition method was monitored during processing using wafer curvature measurements. Stress measurements of the entire Si/SiO2/Pt/SBT stack revealed an overall tensile stress of ∼536 MPa. The greatest increase in tensile stress was recorded for the anneal of the Pt bottom electrode and was due to the thermal expansion mismatch. Deposition of an amorphous SBT layer on the Pt, followed by a low temperature anneal (300°C), had little overall effect on the stress of the stack; however, upon crystallization, significantly more tensile stress was introduced into the stack. To further investigate the effect that stress has on the various electrical properties SBT films, wafers with different stress states were produced and SBT films deposited on them. Initial investigations indicate that SBT films on wafers with a higher tensile stress displayed improved ferroelectric hysteresis and switchable polarization.

The growth of epitaxial thin films of Li1–xNb1–xWxO3 from solution precursors on single-crystal LiNbO3 substrates is reported. An all-alkoxide solution readily gave single phase powders after simply mixing the constituent components, whereas an acetate-alkoxide system required additional solution processing stages to give phase pure powders. Heat treatment of films on single-crystal, basal plane LiNbO3 substrates at 600 °C formed a nanocrystalline, porous film which was converted to an epitaxial film after heating to 800 °C. Measurements of second harmonic generation in powders indicate an increase in SHG efficiency with increasing tungsten content. Optical absorption data for films were calculated using reflectance and transmittance spectroscopy data, and indicate a decrease in bandgap with increasing tungsten.

SrBi2Ta2O9 (SBT) films have received considerable attention for use as nonvolatile memory elements. We have developed a process to prepare SBT films with good ferroelectric properties at low temperatures. In this paper, we will present strategies used to optimize the properties of the films including film composition, the nature of the substrate (or bottom electrode) used, and the thermal processing cycle. Under appropriate conditions, ∼1700A films can be prepared which have a large switchable polarization (2Psw >10μC/cm2), and an operating voltage ≤2.0V.

The spatial distribution and atomic mobility of Li ions in the solid solution system Li1-xNb1-xWxO3 (0 ≤ x ≤ 0.5) have been studied using solid-state NMR techniques. To maintain charge balance, for each tungsten atom substituting on a niobium site, a lithium vacancy is produced in the lithium sublattice. 6Li magic angle spinning experiments reveal multiple lithium sites, attributed to distributions of niobium and tungsten neighbors. Dipolar 7Li second moments measured at low temperature (−100 °C) depend linearly on lithium content, consistent with a random distribution of vacancies. Variable temperature (−20 to 550 °C) 7Li NMR studies as a function of composition give evidence for two distinct motional processes: at low temperatures (near 0 °C) a local hopping process involving only a minority of the lithium ions present is activated. At high temperatures (300 °C and above, depending on substitution levels) long-range diffusion involving all the lithium atoms is evident on the NMR time scale. As the subs...

A solution precursor method based on metal alkoxides was used to produce epitaxial LiNbO3 thin films, ≈200 nm thick, on (0001) sapphire substrates. Transmission electron. microscopy revealed that the major cause of surface roughness in these films was grain boundary grooves between mosaic grains with misorientations ≤5°. It is postulated that these low angle boundaries directly result in surface grooving and roughness. The epitaxial films also contained two distinguishable variants in the film/substrate interfacial plane, namely, an aligned variant, and a 60° rotated variant, . A seeded grain growth method was used to minimize the presence of the 60° rotated variant. An epitaxial buffer layer of Fe2O3 was used to lower the mismatch strain, eliminate the 60° rotated variant, and reduce the mosaic nature of the LiNbO3 film. X-ray rocking curve full-width-at-half-maximum (FWHM) values measured on the film peak indicate that the mosaic character can be reduced from 1.5° to 0.76° by using a buffer layer.

The electromechanical properties of sol-gel derived ferroelectric Pb(Zro.53Tio.47)O3 (PZT 53/47) thin layers deposited on silicon were determined as a function of fieldstrength, measurement frequency and total thickness. Both electrically-induced strains (e) and piezoelectric properties (d33) were characterized by interferometry. Dielectric spectroscopy and polarization switching (P-E) measurements were determined for comparative purposes. An asymmetry between forward and the reverse bias conditions in the e-E displacements was found for both 5-layer deposited and 9-layer deposited structures. However, no asymmetry was observed in the P-E hysteresis characteristics. In addition, the electrically-induced strains and the piezoelectric response were found to be dependent on measurement frequency. No significant frequency dependence was observed in the polarization or dielectric responses. The results are discussed in terms of a possible clamping effect for polarization switching.

The electromechanical properties of sol-gel-derived ferroelectric Pb(Zr0.53Ti0.47)O3 (PZT 53/47) thin layers deposited on silicon were determined as a function of field strength, measurement frequency, and total thickness. Both electrically induced strains (∊) and piezoelectric properties (d33) were characterized by interferometry. Dielectric spectroscopy and polarization switching (P-E) measurements were determined for comparative purposes. An asymmetry between forward and the reverse bias conditions in the ∊-E displacements was found for both five-layer deposited and nine-layer deposited structures. However, no asymmetry was observed in the P-E hysteresis characteristics. In addition, the electrically induced strains and the piezoelectric response were found to be dependent on measurement frequency. No significant frequency dependence was observed in the polarization or dielectric responses. The results are discussed in terms of a possible clamping effect on polarization switching.

A review is given of the sol-gel processing of electrical and magnetic ceramics. Materials include, SnO2,In2O3, WO3, V2O5, VO2, ZrO2, ZnO, BaTiO3, YBa2Cu3O7−δ, Al2O3, 2MgO · 2Al2O3 · 5SiO2, SiO2. 3Al2O3 · 2SiO2, PbTiO3, Pb(Zr,Ti)O3, (Pb, La)(Zr,Ti)O3, LiNbO3, Pb(Mg 1 3 Nb 2 3 )O3, Pb(Zn 1 3 Nb 2 3 )O3, Pb(Sc 1 2 Ta 1 2 )O3, Fe2O3, (Bi,Y)3Fe5O12, and BaFe12O19. Details are reported for the synthesis routes and the fabrication of ceramic components, including conductors, resistors and insulators, and includes, electronic and ionic properties, varistors, thermistors, superconductors, dielectrics, ferroelectrics, magnetics, and microelectronic materials.

The properties of thin layer ferroelectrics appear to differ, sometimes considerably. from those of bulk ceramics of the same composition. Most notably, a broadening of the temperature dependent dielectric anomaly, an increase in the coercive field and a decrease in the remnant polarization are frequently reported. Recent advances in processing thin layers by chemical methods, and in sol-gel processing in particular, have resulted in the capability of fabricating thin layer fermelectrics in which variations in phase composition and microstructure can be. controlled and minimized. In this work. single phase perovskite thin layers of lead zirconate. titanate (PZT) with a composition near the morphotropic phase boundary (Zr/Ti = 53/47) were deposited onto platinized silicon substrates by spin-casting pre-hydrolyzed alkoxide solutions. Ferroelectric and dielectric properties are reported as a function of layer thickness and discussed in terms of an interface effect, series impedance model, and the ac...

The piezoelectric properties of ferroelectric and antiferroelectric thin layers were investigated by interferometry as a function of frequency and dc electric bias. Materials included: a ferroelectric lead zirconate titanate (PZT) with a Zr/Ti ratio of 53/47; a relaxor ferroelectric La‐modified PZT with a Zr/Ti ratio of 70/30 and a La content of 7.8 at. %; and antiferroelectric lead zirconate. The hysteretic behavior of the piezoelectric coefficient due to polarization reversal was also studied. The layers were prepared by a sol‐gel method, and were found to have properties similar to bulk ceramics. Significant strain levels could be achieved in the materials due to the relatively high electric strengths supported in thin‐layer form. Polarization was found to be completely switchable between forward and reverse directions; however, the strain levels generated by switching were found to be inequivalent. In addition, pronounced piezoelectric relaxations and strong piezoelectric losses were observed.

This paper reports on infrared spectroscopy that was used to monitor and characterize solutions used in the preparation of PZT 53/47 powders, dried gels, and thin layers deposited on platinized silicon substrates. It was found that careful control of the chemistry of the precursor solutions, in particular the control of the formation of esters and their elimination, resulted in reproducible solutions which could be used to prepare thin layers with superior properties. In addition, it was found that phase development and microstructure were related to the precursor chemistry. Single-phase perovskite layers with uniform microstructures resulted from ester-free solutions and were suitable for ferroelectric applications (P[sub r] [approximately] 22 [mu]C/cm[sup 2], E[sub c] [approximately] 80 kV/cm, K [approximately] 800, tan [delta] [approximately] 0.01).

Acrylic (PAN) fibers with a novel coiled morphology as precursors for semiconducting carbon IR detection elements were prepared using a “hybrid” spinning technique combining principles from standard wet and dry spinning methods. Fiber structure and morphology were found to depend on furnace temperature and coagulation conditions. The highest-density fibers were formed at a furnace temperature of 180°C and a coagulation bath composition of H 2 O:DMF = 3:1 at 19°C. Fibers with diameters of 100–200 μm were obtained, which when fired had resistivities in the range ≈ 3–70 Ω cm, and thermistor constants of B ≈ 1300–2500 K. Their application as IR detection elements is reported.

The global market for wireless sensor networks in 2010 will be valued close to $10 B, or 200 M units. TPL, Inc. is a small Albuquerque based business that has positioned itself to be a leader in providing uninterruptible power supplies in this growing market with projected revenues expected to exceed $26 M in 5 years. This project focused on improving TPL, Inc.'s patent-pending EnerPak{trademark} device which converts small amounts of energy from the environment (e.g., vibrations, light or temperature differences) into electrical energy that can be used to charge small energy storage devices. A critical component of the EnerPak{trademark} is the supercapacitor that handles high power delivery for wireless communications; however, optimization and miniaturization of this critical component is required. This proposal aimed to produce prototype microsupercapacitors through the integration of novel materials and fabrication processes developed at New Mexico Technology Research Collaborative (NMTRC) member institutions. In particular, we focused on developing novel ruthenium oxide nanomaterials and placed them into carbon supports to significantly increase the energy density of the supercapacitor. These improvements were expected to reduce maintenance costs and expand the utility of the TPL, Inc.'s device, enabling New Mexico to become the leader in the growing global more » wireless power supply market. By dominating this niche, new customers were expected to be attracted to TPL, Inc. yielding new technical opportunities and increased job opportunities for New Mexico. « less

Wireless sensors provide solutions to otherwise intractable problems where it is impractical to deploy wired sensors. One of the biggest challenges facing wireless sensors is power. Advances in power management and battery technologies may soon enable three year life from primary batteries, but will require stringent control over sensor operation that, in many applications, will place unacceptable limits on the performance of parameters such as data rate or transmission range. Energy harvesting provides a solution to these problems, but tends to be limited by the inherent low and fluctuating level of ambient energy. In this presentation we will demonstrate a system that combines smart, ultra-low power charge management circuitry and electrochemical energy storage that is compatible with any energy harvesting technology. This building block is essential for realizing a power system that can replace batteries in end-user systems providing the benefits of energy harvesting technology while mitigating the drawbacks.

Organic polymeric materials, often used as ceramic processing aids to assist in the fabrication of green bodies, are thought to be of a temporary nature, being easily removed by thermolysis at temperatures between 250{degrees} and 600{degrees}C. This paper reports the interaction of various poly(vinyl butyral) binders with fine, high-purity alumina powder investigated using variable-temperature Fourier-transform infrared spectroscopy and thermal gravimetric analysis. It was found that there was interaction between the functionality of the polymers and the surface of the alumina powders. If these interactions are strong enough to persist to initial sintering temperatures, the polymers would not then be merely innocuous temporary processing aids, but could have an effect on the development of ceramic microstructures.

Wireless sensors provide solutions to otherwise intractable problems in homeland defense and security, building automation, industrial process monitoring and control, structural health monitoring in bridges, aircraft, buildings and ships and a host of applications where the cost or feasibility of deploying wired sensors is impractical. The biggest challenge facing wireless sensors is power. While advances in power management and battery technology may enable 3 to 5 year battery life, in many applications even this is not sufficient. Energy harvesting techniques show potential to provide long lasting power, but suffer from low power density values, meaning that they must be oversized to deliver power for short duty cycle communications functions. In this paper we demonstrate a solution that draws on the benefits of energy harvesting for long life, and microbatteries and microsupercapacitors to provide back-up and pulse power capabilities without the need for refueling or recharging.

The method of rapid thermal processing (RTP) has been suggested to be a means by which the formation of intermediary phases in sol-gel derived Pb(Zr,Ti)O/sub 3/ (PZT) thin layers can be suppressed before the crystallization of the desired perovskite phase. However, the dependence of densification and crystallization processes in sol-gel derived materials on thermal processing conditions such as heating rate, /spl alpha/, and firing temperature, T/sub f/, can lead to differences in the properties of otherwise identical materials prepared by different thermal profiles. In this paper, the effects of thermal processing conditions on the properties of PZT 53/47 (i.e., Zr:Ti=53:47) thin layers are reported. The evolution of structure after RTP was examined by diffuse reflectance FTIR spectroscopy, and electron microscopy. It was found that crystallization of the perovskite phase shifted to higher temperatures, and the shrinkage normal to the plane of the substrate decreased, with increasing heating rate.

This work investigates temperature and humidity effects on the superhydrophobicity of polyurethane/organoclay nanocomposites. Previous reports of superhydrophobic degradation at decreasing surface temperatures for both low and high humidity were generally conducted in open environments. However, the present setup allows a thermally homogeneous environment, i.e., the temperature of the nanocomposite, air and water droplet are equal with no spatial temperature gradients. In such conditions, results showed stable retention of superhydrophobicity for both low humidity (RH 80%) cool-down cycle, though superhydrophobicity degraded during the warm-up cycle, which was attributed to dew condensation.

The evolution of structure and chemical distribution in sol-gel derived Pb(Zr0.53T10.47)O3 thin layers was monitored by x-ray diffraction, analytical electron microscopy, and diffuse reflectance Fourier transform infrared spectroscopy. Electron microscopy confirmed the as-deposited coatings were amorphous with short-range order. Medium-range order developed on heat treatment, and chemical heterogeneity was observed at the nanoscale. The extent of compositional heterogeneity decreased with increasing temperature. Above 500 °C, the coatings crystallized into an intermediate phase which converted to the perovskite phase above 600 °C.