CaBi4Ti4O15 growth on different Platinum substrates was carried out through a sol-gel method. Higher crystallization temperature and 20% excess Bi decreased pyrochlore contents in the CaBi4Ti4O15 films. Repetition through coating, calcination and crystallization decreased void formation on the surface. C-axis oriented thin film could be grown on sputtered platinum substrates with low Pt (200) orientation. On electroplated Pt substrates, (119) oriented CaBi4Ti4O15 thin film was grown, suggesting surface roughness of Pt substrates is a crucial factor for orientation control of sol-gel derived CaBi4Ti4O15 thin film.

This paper reports the effect of a Pd/Sn catalyst treatment process on the adhesion of electroless copper deposited onto a glass substrate. Adhesion of the copper varied with catalyst treatment time: short or extended catalyst immersion times led to lower adhesion. In this work silanisation of the glass surface with (3-aminopropyl)-trimethoxysilane was used to provide a layer of functional molecules to assist the adhesion of the Pd/Sn catalyst. Surface analysis of the catalyzed glass was carried out by X-ray Photoelectron Spectroscopy (XPS) and together with Time-of-Flight Secondary Ion Mass Spectrometry, showed that the Pd/Sn structures changed with increasing immersion time in the catalyst bath. The Pd XPS core level peaks indicated that Pd(0) became more significant in the catalyst layer than Pd(II) with increasing immersion time. Tape peel testing was used to assess the adhesion of the coatings: thin layers adhered well to the glass, but for layers thicker than 160 nm tape tests removed large areas. The failure surfaces of copper layers peeled off the glass were also examined by XPS which indicated that the failure occurred between the copper and catalyst.

Alumina is one of the most widely used oxide ceramic material. It exists in many metastable forms, among which is the thermodynamically stable α phase, obtained upon severe thermal treatment. Sintering of alumina is generally performed in several stages: first, phase transitions towards the stable α phase followed by its densification. The first step is strongly dependent on the crystallinity of initial powders. By controlling this parameter, it is possible to optimize the sintering properties, in particular by decreasing the phase transition temperature. This effect has been studied for alumina elaborated in sub- and supercritical fluid media. This work highlights the possibilities to obtain, according to the nature of the fluid, different kinds of transition alumina: boehmite AlO(OH) or amorphous Al2O3. The sintering processes of these powders all lead to α-alumina, however, different microstructures and densities can be obtained. A significant shift towards lower λ/α phase transition temperature is also observed when amorphous alumina is considered, compared to boehmite. The transfer of this know-how to the design of core-shell nanoparticles and film deposition onto copper heat sinks is investigated to develop nanostructured ceramics for telecommunications and electronics.

TiO2 nanotube arrays had been selected as electron transport material incorporate with P3HT:PCBM blended polymer to fabricate the hybrid organic-inorganic solar cells. Well aligned TiO2 nanotube arrays has been synthesized though the liquid phase deposition by using ZnO nanorod arrays as templates. Three types of dyes (viz. NKX-2677, D149, N719) were adsorbed onto the surface of TiO2 nanotube arrays to increase the interfacial contacts between the organic polymer and inorganic metal oxide. Surface modification with NKX-2677 exhibited remarkable improvement of the cell efficiencies in terms of current density, open circuit voltage, and fill factor as compared with those of other dyes.

The growth of high-quality crystalline ZnO thin films on ZnO bulk substrates and of amorphous In-Ga-O and Ga-Al-O thin films has been demonstrated by using the solution-based cost-effective and environmental friendly ultrasonic spray assisted mist-CVD method. The homoepitaxial ZnO thin films with atomically flat surfaces were successfully grown on Zn-polar ZnO substrates via a step-flow growth mode, in spite of different miscut angles of the substrate, at the furnace temperature of 1000°C. The compositions and optical absorption edges of the amorphous In-Ga-O and Ga-Al-O thin films were controlled by means of the concentration ratios of [In]/([In]+[Ga]) and [Al]/([Al]+[Ga]) in the starting solutions.

Ionic resistive switches are emerging as a potential successor for flash in non!volatile memory applications. In ionic switches, metal cations migrate through a solid electrolyte forming filaments on an inert cathode that results in an abrupt increase in conductivity. This process is reversible, and the switches may be reverted to a low!conductive state. These switches have low transition voltages and fast read speed. The low switching energy potentially makes them more scalable than many other resistive memories. Silver Sulfide Resistive switches have been fabricated by sulfidizing evaporated silver films in Sulfur solutions. XPS is used to quantify stoichiometry of resultant films. SEM and AFM indicate that surface roughness increases with sulfidation time as the bulk silver film is consumed in forming the silver sulfide. XRD has confirmed presence of the acanthite phase of silver sulfide in the films. The entire process is performed at temperatures below 200C, so the devices are potentially stackable over conventional CMOS substrates in a BEOL process, and are applicable to printable electronics on plastic substrates. Initial characteristics measured on these cells are very promising, exhibiting low energy switching and good programming margins. Write/Erase voltages for cells were about 400mV and !200mV respectively. Ron/Roff ratios range from 10 to as high as 10, 000 depending on process conditions. Impact of bath concentration, bath temperature and post!annealing on the silver sulfide film structure are studied. Ionic switching is demonstrated in the films.

Electrochemical co-depositions of indium (In) with selenium (Se) and gallium (Ga) with selenium were carried out to obtain high-quality In-Se and Ga-Se films. The approach utilized full potential of complexation for the first time by using aqueous electroplating solutions containing complexing agents at alkaline regime. Complexing agents were employed to solubilize In and Ga ions at high pH and to bring their reduction potentials down, closer to that of Se. Since no appreciable complexation occurred between Se and the complexing agents, Se reduction potential could be independently controlled by the amount of dissolved Se. Tartrate and citrate were determined to be suitable complexing agents for In and Ga. By optimizing the concentrations of the metal salts, the complexing agents, the selenium source, pH and the electrodeposition current density, it was possible to obtain adherent and smooth In-Se and Ga-Se films with high repeatability and controllable In/Se and Ga/Se molar ratios.

ZnO thin films were deposited in a solution with Zn(NO3)2 and DMAB from 60 to 80°C. The effects of cation additives such as Mg, Ga and Al in a aqueous solution were investigated on surface morphology, crystallographic structure and growth rate. By adding 1E−4 mol/l of Ga or Al, the growth rate was enhanced from 0.13 m/h to 0.35-0.38 m/h. In addition, the surface morphology became flat in the case of Al addition.

An ITO film on an SiO2 substrate was prepared from spin-coated nano-particles using a simple thermal process and photo irradiation process. The effects of the excimer lamp and excimer laser on the resistivity of the film were investigated. When the film is 40 nm thick, the combined two-step irradiation by an excimer lamp and laser in N2 is effective for the preparation of the ITO film with a lower resistivity. Using the two-step irradiation and one-step KrF irradiation in N2 at room temperature, the resistivity of the ITO film was 5.94×10−4Ωcm. On the other hand, when using the thermal process, the resistivity of the film sintered at 500 °C in N2 was 4.10×10−3Ωcm. The differences in resistivity are discussed on the basis of the microstructure using SEM, XRD and Hall measurements.

We demonstrate a novel technique using supercritical carbon dioxide (scCO2) fluid for lowering processing temperature of sol-gel-derived metal oxide thin films. The film processing was performed in a hot-wall closed vessel filled with scCO2 fluid. The effects of fluid temperature and additives on the sol-gel synthesis reaction under scCO2 fluid were also investigated. Precursor films of titanium dioxide (TiO2) prepared on silicon wafer and silica glass by sol-gel coating using Ti-alkoxide were converted to crystalline TiO2 (anatase) films successfully by treatment in scCO2 without additive agent at a fluid pressure of 15 MPa and at a substrate temperature of above 250°C, which is significantly lower than the processing temperature of conventional sol-gel deposition. Furthermore, additive agents such as water (H2O) and nitrogen-oxygen mixture (N2-O2) promoted the decomposition and crystallization of precursor films in scCO2 fluid to form the crystalline TiO2 (anatase) films at a substrate temperature at as low as 200°C although it also produced surface absorbates consisted of hydroxides on the film surface. The experimental results suggested that the hydrolysis and polymerization reactions of Ti-alkoxide in the precursor films were proceeded by the scCO2 processing to form titanium-oxygen (Ti-O) networks and that byproducts such as alcohols were removed from the resulting films.

The deposition of amorphous InGaZnO4 (a-IGZO) semiconductor film, via a sputtering process, has been demonstrated in the literature. In this paper, we present a solution method as an alternative to obtain this semiconducting film. The dispersible IGZO colloids is formed first by co-precipitation of precursors, followed by hydrothermal treatment at 200°C for 1 hour and using CMC as the dispersion agent. The crystalline colloid would become amorphous when it was heated at above 250°C. The TFT structure was made by growing a dielectric silica layer using the CVD method, a metal layer using the sputtering method, and an active IGZO layer using the solution method. This device exhibits low operating voltage, the mobility is about 2cm2V−1s−1 and the Ion/Ioff ratio is 104. Further improvement in processing is needed.

Various flexible electronic devices have been intensively studied and developed in this decade. Most of consumers expect to obtain these flexible electronic devices in the next decade. The spread of flexible electronic devices depends on the process costs and material costs. Today prices of materials and energy sources are continuously increasing. Therefore, using of expensive materials and wasteful processes for fabricating electronic devices should be reconsidered. Printing techniques, a representative solution process, are inexpensive and very effective for mass production of electronic devices. We have developed a low-temperature process for fabricating flexible printed patterns of metals and semiconductors by using relatively inexpensive commercial pastes. A characteristic of our process is to utilize mechanical energies for sintering particles contained in pastes. In our process, the precise three-dimensional pressure control brings about the improvement of electrical properties in the printed patterns, the preservation of pattern accuracy and the mechanical durability of the printed patterns. In our experiment, we have already fabricated very low resistivity metal patterns (about 6×10−6Ω·cm) at ca.120°C without using any kinds of nano-particle paste, and also fabricated metal oxide semiconductor patterns.

Room temperature sol-gel synthesis and optical characterization of highly transparent silica glass for photovoltaic (PV) applications is presented in this paper. Tetraethyl orthosilicate (TEOS), Ethanol, Hydrochloric acid (HCl) and deionized water were used as precursors in the volumetric ratio of 4:4.3:0.1:3.2 ml. Silica glass of thickness in the range of 0.5-1 cm were obtained with an average transmittance of 93% and absorption coefficient (α) of 0.08 cm−1 in a wide wavelength window of 350-1100 nm. Application of the developed sol-gel silica glass on solar ray concentration, anti-reflective coating (ARC) and effect of surface passivation on silicon wafers were examined. Carrier lifetime of the sol-gel silica passivated silicon substrate was 16 s and the calculated surface recombination velocity of the was 2200 cm/sec. Very low value of α, high transparency in a wide spectral window and effective surface passivation on silicon suggest that sol-gel processed silica glass can be a potential cost effective candidate for different PV applications.

Maximizing power and energy densities of ultracapacitors requires configuring redox-active materials in specific architectures that: 1) maximize electrolyte-electrode contact area, 2) minimize transport distances for both electrons and charge compensating species, and 3) minimize transport barriers. We have developed a simple solution-based method, using an organic template, that enables us to introduce hierarchical porosity in ruthenium oxide down to the nano-scale by controlling the oxidative crystal growth of RuO2. The high capacitances of the resulting nanostructured electrodes were found to be comparable to hydrous ruthenium oxide formed under dramatically different conditions. Materials characterization reveals that the organic template directs structure formation and promotes hydroxyl retention.

Polymer/ceramic nanocomposites provide a means of combining the high permittivities (εr) of metal oxide nanoparticles with the solution-processability and high dielectric strength of polymeric hosts. Simple mixing of nanoparticles and polymers generally results in poor quality nanocomposites due to the agglomeration of nanoparticles and poor miscibility of nanoparticles with host materials. We have shown that surface modification of metal oxide nanoparticles with phosphonic acid-based ligands affords robust surface modification and improves the processiblity and the quality of the resulting nanocomposites. We report on the use of phosphonic-acid modified barium titanate (BaTiO3, BT) nanoparticles in dielectric nanocomposites and their applications to high-energy-density capacitors and solution-processable high permittivity gate insulators in organic field-effect transistors (OFETs). Surface modification of BT nanoparticles enabled the formation of high quality nanocomposite thin films with ferroelectric polymer hosts such as poly(vinylidene fluoride-co-hexafluoropropylene), P(VDF-HFP), with large volume fractions (up to 50 vol. %), which are potentially useful materials for electrical energy storage. Similarly, the use of phosphonic acid-modified BT nanoparticles in cross-linked poly(4-vinylphenol) (PVP) allowed to form gate insulators for OFETs. High quality nanocomposite thin films at high nanoparticle volume fractions (up to 37 vol. %) with a large capacitance density (∼50 nF/cm2) and a low leakage current (10−8 A/cm2) were obtained. Pentacene-based p-type OFETs using these nanocomposites showed a large on/off current ratio (Ion/off 104 ∼ 106). We will also present the results from a recent experimental and theoretical study where the BT nanoparticle volume fraction was systematically varied in P(VDF-HFP) host, εr = 11, to find the optimum permittivity and dielectric strength, which provided a guideline for the optimization of the volume fraction for achieving maximum energy density.

Printable devices have been attracting considerable interest because of their application to flexible large-area devices in low cost printable electronics. In order to fabricate such devices, it is necessary to discover a passivation film and develop an efficient process for its preparation. We have previously reported that silicone oxide film is obtained with high density by UV irradiation to silazane compound film at low temperature [1]. The silicon oxide film has electric resistivity more than 10−15 Ωcm and electric strength more than 7 MV/cm. In order to apply the film to passivation layer in printable device, in this paper, preparation of nano-composite film with silicon oxide and clay mineral was investigated.

We report the binding and conductivity characteristics of PbSe nanocrystal quantum dots which have different ligands on the surface. The PbSe nanocrystal quantum dots were surface functionalized using chemical treatment. The results of post-treatment analysis show that the PbSe surface can be successfully functionalized with various ligands based on thiol- and amine-molecules (e.g., oleic acid, dodecanethiol and butylamine). Conductivity measurements performed using a metal-semiconductor-metal structure indicate that there is an increase of conductivity as the length of the ligand connecting the quantum dots is reduced.

A method for rapid electrical sintering (RES) of nanoparticle structures on temperature-sensitive substrates is presented. For an inkjetted silver nanoparticle conductor, a conductance increase of five orders of magnitude is demonstrated to occur in a timescale that typically varies between a few and one hundred milliseconds depending on process parameters. Furthermore, most of the conductance change takes only a few microseconds. The achievable final conductivities are within a factor of two from the bulk silver conductivity, as calculated using the external geometric dimensions of the structure ignoring porosity. The method is also applicable to other inorganic conductors such as indium-tin-oxide (ITO). More generally, the method offers a versatile tool in nanotechnology for electrical functionalization of nanoparticle structures. The method is also potentially suited for mass production.

Ferroelectric film-on-foil capacitors hold special promise to replace discrete passive components in the development of electronic devices that require greater performance and smaller size. We have deposited Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT) films on base metal foils to form film-on-foil capacitor sheets that can be embedded into printed circuit boards. The rootmean-square surface roughness was determined to be ≍3 nm for 1.15-μm-thick PLZT films on LaNiO3-buffered Ni foils. The following dielectric properties were measured: relative permittivity of ≍1300 and dielectric loss (tan δ) of ≍0.05, leakage current density of 6.6 × 10−9 A/cm2 at 25°C and 1.4 × 10−8 A/cm2 at 150°C, and mean breakdown strength >2.5 MV/cm. A remnant polarization (Pr) of ≍33 μC/cm2 and coercive field strength (Ec) of ≍50 kV/cm were observed with a maximum voltage of 300 V applied during the P-E loop measurement. The energy storage capability of the dielectric film is ≍45 J/cm3.

The organosilicon nanoclusters (OSI) and organogermanium nanocluster (OGE) which have a few nanometer sized silicon or germanium cluster and organic groups bonded to the nanocluster surfaces show solubility in common organic solvents and good film processability by solution coating method. Using the coating films as precursors, inorganic silicon and germanium films were prepared by heat treatment in vacuo and laser annealing. The structural changes of the Si and Ge skeletons of the OSI and OGE by heat treatment and laser annealing were investigated by Raman spectroscopy. The laser-annealed films showed Raman bands assigned to the polycrystalline structure. The micropatterning of polycrystalline Ge by laser direct writing method was demonstrated. The organosoluble OGE is expected to be applicable as a germanium ink which gives polycrystalline Ge film.