Thin films of MgIn2O4 spinel, which is a recently discovered TCO material, were deposited on MgO (100) surface by PLD. The thin films were prepared under low oxygen partial pressure to enhance formation of oxygen vacancies, from which carrier electrons were generated. X-ray analyses and AFM observations suggest epitaxial growth of the grains with diameter of 100∼200nm. The grains showed strong orientations both along the normal of the thin film and in plane. Epitaxial growth of the spinel was also confirmed by high-resolution transmission electron microscopic observations. The lattice image of the interface region suggests formation of structural imperfections such as dislocations, grain boundaries and amorphous phase in significant fraction. Strong optical absorption due to electron carriers was detected in near infrared region. Very large Burnstein-Moss shift was observed in ultraviolet region, and the optical band gap was estimated to be 4.3eV. DC conductivity observed was 4.5×103Scm−1, which is the highest value reported for the material so far. Concentration and Hall mobility of carrier electrons were found to be 2.1×1021cm−3 and 14cm2V−1s−1, respectively.

The properties of thin oxide films such as Y2O3, ZnO and Ba0.5Sr0.5TiO3 grown using an in situ ultraviolet (UV)-assisted pulsed laser deposition (UVPLD) technique have been studied. With respect to films grown by conventional PLD under similar conditions but without UV illumination, the UVPLD grown films exhibited better structural and optical and electrical properties, especially for lower substrate temperatures. They also exhibited a better stoichiometry and contained less physisorbed oxygen than the conventional PLD grown layers. These improvements can be traced to several factors. Firstly, deep UV photons and ozone ensure a better in situ cleaning of the substrate prior to the deposition. Secondly, the presence of more reactive gaseous species like ozone and atomic oxygen formed by photodissociation of molecular O2 promotes the growth of more oxygenated films. Thirdly, absorption of UV photons by adatoms could result in an increased of their surface mobility. All these factors have a beneficial effect upon crystalline growth, especially for moderate substrate temperatures. For optimised growth conditions, the crystalline quality and properties of ultraviolet-assisted pulsed laser deposited films was similar to that of films grown using conventional PLD at substrate temperatures of at least 200°C higher.

For the growth of thin zinc group metal oxide films [i.e. cadmium oxide (CdO), cadmium stannate (Cd2SnO4), and zinc oxide (ZnO)] via metal-organic chemical vapor deposition (MOCVD), volatile Cd and Zn precursor families are needed. Starting with Cd, β-ketoiminates of varying substitution were prepared to elucidate structure-property relationships. The nature of the ligand substituents strongly influences the melting point (liquid precursors are desired). Unlike conventional Cd β-diketonates, these complexes are monomeric as determined by x-ray crystallography. Despite these advantageous characteristics, attempts to grow CdO thin films in a cold-wall MOCVD reactor using two such derivatives were not successful. This class of Cd complex appears to decompose thermally with time-- a likely cause of the poor performance. Therefore, a new series of more thermally stable Cd precursors was sought. Using the chelating diamine N,N,N1,N1-tetramethylethylenediamine (TMEDA), monomeric β-diketonates were prepared. The molecular structure of Cd(hfa)2(TMEDA) (hfa = 1,1,1,5,5,5-hexafluoropentane-2,4-dionate) confirms the monomeric structural assignment. This series of Cd complexes is appreciably more volatile and sublime more cleanly than the aforementioned β-ketoiminates, as determined by vacuum thermogravimetric analysis (TGA). In addition to this advantageous characteristic, these complexes are easily prepared under ambient laboratory conditions from commercially available starting materials in a single step. Following the protocol established for Cd, a volatile series of Zn precursors was also prepared. For the Zn series, the melting point was effectively tuned through variation of both the β-diketonate and diamine ligands. The use of the Cd and Zn β-diketonate precursors in the successful growth of CdO and ZnO thin films, respectively, by MOCVD is also presented.

Metal oxides exhibit a wide variety of properties originating mainly from strong electron correlation. Electronic properties of oxides had been utilized mostly in the bulk form till recently and people frequently observed significant changes in such properties when these materials were converted into thin films. For the electronic application in recent years, hybridization and integration of materials in thin film forms are becoming more and more important. In view of our recent studies on high-Tc superconducting junctions and ZnO light emitting devices, this paper is devoted to stimulate the exploration of oxides as new innovative electronic materials by discussing the control of epitaxial thin film growth.

KrF excimer laser ablation technique is used to fabricate the ferroelectric Pb(ZrxTi1−xO3)(PZT) capacitor on Si(100) substrate. The superconducting YBa2Cu3O71−x(YBCO) and the colossal magnetoresistive La0.8sr0.2MnO3(LSMO) thin films are used as bottom electrodes for the ferroelectric capacitive structure. The YBCO and LSMO films were studied to understand the interface problems with perovskite oxide films. The fabricated PZT/YBCO/YSZ/Si capacitor shows the ferrolectric properties of the remanent polarization of 20pC/cm2 and the coercive field of 40 kV/cm. Post-thermal annealing improves the ferroelctric properties and the results are comparable with that of the PZT/YBCO/MgO(100) structure. The leakage current of the PZT capacitor is discussed.

Thin films of SrVO3 have been grown on (100)LaAlO3 and TiN buffered (100)Si substrates by pulsed laser deposition. The films were deposited in temperature range of 450°C – 750°C and under ambient oxygen pressure between 101−6 and 101−2 Torr. Their structural properties were characterized using a four-circle x-ray diffractometer. High quality SrVO3 films were obtained at growth temperatures above 500°C without post annealing. Heteroepitaxial relationship of < 100 >SrVo3 ∥ < 100 >LaAOl3 and <100>SrVo3∥ < 100 >TiN ∥ < 100 >Si were observed for films deposited at ≤ 550°C. X-ray photoelectron spectroscopic studies of the films suggest that the vanadium is mainly tetravalent and pentavalent. Charge transport measurements show that the films vary from semiconducting to highly conducting for different growth conditions. Resistivity of a few micro-ohm cm was recorded for some of the epitaxial SrVO3 films.

The optical and structural properties of ZnO/MgZnO superlattices were investigated by transmission electron microscope, transmission measurement and photoluminescence. The uncoupled wells ranged in thickness from ∼ 30 Å to 75 Å Modulation of the Mg content was observed in Z-contrast TEM indicating the alloy composition was periodic. The density of stacking faults in the superlattice was extremely high, however the photoluminescence in the narrowest well case was blue shifted, and substantially brighter than comparable bulk layers of ZnO and MgZnO indicating that the emission was enhanced. Excitonic features were observed in the optical absorption spectra and also revealed that diffusion of Mg from the barrier layers into the well was occurring.

The single quantum well heterostructures of MgZnO/ZnO/MgZnO were grown on c-plane sapphire substrate by pulsed laser deposition. The well width was varied from 10 nm to 40 nm by controlling the deposition rate via number of laser pulsed on ZnO target. Using photoluminescence spectroscopy, we have observed a blue shift with respect to a thick ZnO reference sample when the well width was decreased. These results were fitted with calculations based on the simple square well model using the appropriate electron and holes effective masses. The quantized-energy and band offset as a function of well width, growth conditions, interface roughness, and possible quantum size effects on the quantum wells are discussed.

We have evaluated lanthanum strontium cobalt oxide (La0.5OSr0.50COOx; LSCO 50/50) as a candidate “transparent” electrode for use in an electrostatic shutter-based infrared sensor protection device. The device requires that the electrode be transparent (80% transmission) and have moderate sheet resistance (300 – 500 Δ/sq.). To meet these needs, the effects of post-deposition annealing on the resistivity and optical absorption characteristics of sputter deposited LSCO thin films were studied. The as-deposited films were characterized by an absorption coefficient of ∼ 12,500 cm1−1 and resistivities of ∼ 0.08 to 0.5 Δ-cm. With annealing at 800°C, the resistivity decreased to 350 νΔ-cm, while the absorption coefficient increased to ∼ 155,000 cm1−1. By using a post-deposition annealing step at 800°C and controlling film thickness, it appears that a standard LSCO 50/50 material may possess the requisite conductivity and optical transmission properties for this sensor protection device.

Lanthanide oxide thin films are of increasing scientific and technological interest to the materials science community. A new class of fluorine-free, volatile, low-melting lanthanide precursors for the metal-organic chemical vapor deposition (MOCVD) of these films has been developed. Initial results from a full synthetic study of these lanthanide-organic complexes are detailed.

We have succeeded in an epitaxial growth of bismuth tungstate (Bi2WO6, BWO) thin films, one of the bismuth layer-structure ferroelectrics (BLSF), on SrTiO3 (001) single crystal substrates by a spin coating process. BLSF are known to be one of the promising materials for ferroelectric random access memory (FeRAM) devices. A homogeneous coating solution was prepared with tungsten hexachloride and bismuth 2-ethylhexanoate as raw materials, and 2-(2-methoxyethoxy) ethanol and formamide as solvents. The as-coated thin films were sintered at temperatures from 500 to 800°C for lh in air. BWO crystallized at temperatures above 500°C. Any crystal phase was not observed in the thin films except for (001) phases of BWO in the XRD patterns. It was confirmed that the thin film was growing epitaxially by measurement of XRD pole figure. The crystallographic relationship of the film and substrate was BWO(001)//STO(001), BWO[110]//STO[100].

We report on the properties of Ta2O5 thin films prepared by the metalorganic solution deposition (MOSD) technique on Pt-coated Si, n+-Si, and poly-Si substrates. The effects of postdeposition annealing temperature on the structural, electrical, and optical properties were analyzed. The electrical measurements were conducted on MIM and MIS capacitors. The dielectric constant of amorphous Ta2O5 thin films was in the range 29.2-29.5 up to 600°C, while crystalline thin films, annealed in the temperature range 650–750°C, exhibited enhanced dielectric constant in the range 45.6–51.7. The dielectric loss factor did not show any appreciable dependence on the annealing temperature and was in the range 0.006–0.009. The films exhibited high resistivities of the order of 1012–1015 Δ-cm at an applied electric field of 1 MV/cm in the annealing temperature range of 500-750 °C. The temperature coefficient of capacitance was in the range 52-114 ppm/°C for films annealed in the temperature range 500-750°C. The bias stability of capacitance, measured at an applied electric field of 1 MV/cm, was better than 1.41 % for Ta2O5 films annealed up to 750°C.

Lanthanum nickel oxide (LNO) is a conducting ceramic which has potential to be used as electrodes in multilayer ceramic actuators. Thick LNO films have been formed by incorporating nanosized LNO powder (annealed at 700°C, with diameter around 100 nm) into a LNO solution prepared by a metal-organic decomposed ( MOD ) method. Three different weight percents, 2%, 4%, and 10% of LNO powder have been added. The structural variation of the ceramic/ceramic composite film with annealing temperature was studied by X-ray diffraction and differential thermal analysis. The crystallization temperature of the film is found to decrease from ∼590°C to ∼510°C due to the seeding effect introduced by the nano-powder.

The major disadvantage of Ni/NiO cathodes for a Molten Carbonate Fuel Cells (MCFC) application is dissolution of NiO in K/Li electrolyte that significantly decreases the cell lifetime. Thin films of LiCoO2 or LiMg0.05Co0.9502 were prepared on a cathode body in order to protect them against dissolution. For preparation of starting sols the Complex Sol-Gel Process (CSGP) has been applied. These sols have been prepared by adding of LiOH to aq. acetates solution of Co 2+(Mg2+) with ascorbic acid and then by alkalizing them with aqueous ammonia to pH=8. The cathode plates of various dimensions (to several hundreds cm2) have been dipped in these sols and withdrawn at rate a 1.7 cm/s. Commercially sintered Ni plates were always initially oxidized by heating at various temperatures. Their microstructure and mechanical properties as a function of temperature were observed. Heat treatment should be carried out under the dead load of the ceramic plates in order to avoid their waving. The best non-folded plates were obtained by treating them for lh at 550°C. The covered substrates were calcined for lh at 650°C, using low heating ratel°C/min. The presence of LiCoO2 in a deposited coating has been proved by EDS patterns. The resultant film thicknesses were measured by scanning electron microscopy (SEM) on the fractured cross-sections; they ranged from 0.5 to 2νm and depended on sol concentration and viscosity. A 350 hundred hours test in molten carbonates, proved that the cathode bodies covered with LiCoO2 are completely prevented from dissolution of Ni in a molten K/Li electrolyte. Dissolution of LiCoO2 coating was not observed as well. After treatment in a molten electrolyte SEM observations did not show any changes in microstructures and morphology of the covered cathodes.

YbBa2Cu3O7-σ(Yb123) films were formed on SrTiO3(STO)(001) and LaAlO3(LAO)(001) substrates by the dipping-pyrolysis process. Using transmission electron microscopy, we investigated effects of the heat-treatment conditions in the processes of the dipping-pyrolysis method on microstructures of these films. As a result, we found that the high heating rates at the initial and final heat-treatments are necessary for achieving the epitaxial growth of the superconducting films.

The lateral thermal oxidation process of Al0.98Ga0.02As layers has been studied by transmission electron microscopy. Growing a low-temperature GaAs layer below the Al0.98Ga0.02As has been shown to result in better quality of the oxide/GaAs interfaces compared to reference samples. While the later have As precipitation above and below the oxide layer and roughness and voids at the oxide/GaAs interface, the structures with low-temperature have less As precipitation and develop interfaces without voids. These results are explained in terms of the diffusion of the As toward the low temperature layer. The effect of the addition of a Si02 cap layer is also discussed.

Well oriented Bi2Sr2CaCu2O8(Bi2212) superconductor thick films were formed successfully on Cu tapes by liquid reaction between Cu-free precursors and Cu tapes. Cu-free Bi-Sr-Ca-O powder mixtures were screen-printed on Cu tapes and heat-treated at 850-870°C for several minutes in air. Cu-free precursors were composed of BixSrCaOy(x= 1.2-2). In order to obtain the optimum heat-treatment condition, we studied on effects of the precursor composition, heattreatment temperature and time, the screen-printing thickness, and the heat-treatment atmosphere on the superconducting properties of Bi2212 films. Microstructures and phases of films were analyzed by XRD and optical microscopy. The electric properties of superconducting films were examined by the four probe method. At heat-treatment temperature, the specimens were in a partially molten state by liquid reaction between CuO in the oxidized copper tape and the precursors. The non-superconducting phases in the molten state are mixtures of Bi-free phase and Cu-free phases.

A study of the growth morphology and electronic structure of TaOx films on the Ag(100) substrate has been performed to determine the properties of ultra-thin TaOx films without the influence of a mixed interfacial oxide (i.e., a disordered SiO2/TaOx interface for growth on Si). The TaO, films were grown by thermal evaporation of Ta in an oxygen atmosphere of 1 × 101−6 Torr. Growth on a Ag(100) surface held at room temperature results in an amorphous TaOx overlayer, as determined by low energy electron diffraction. The onset of ordering of these films occurs for a post-anneal at ∼500°C. A diffraction pattern that corresponds to a multi-domain overlayer structure is observed for anneals at ∼550°C. Deposition of Ta without oxygen results in the formation of Ta islands. These results indicate that there is a very weak adsorbatesubstrate interaction. Photoemission measurements of the TaOx films show the formation of a band gap with the valence band maximum residing at 3.5 eV below the Fermi level. Core level shifts of ∼3.5 eV are observed for the Ta with no indication of metallic Ta at the surface.

Direct synthesis from aqueous solution (DSAS) is the method for synthesizing ceramic oxides in crystalline state directly from aqueous solution at ordinary temperature and ordinary pressure. DSAS is advantageous because of the applicability to making films with wide areas and/or complicated shapes with no requirement of vacuum or high temperature. Micro patterning of materials having high dielectric constant is important for manufacturing electronic devices such as dynamic random access memory, ferroelectric random access memory and so on. By using DSAS, TiO2 thin film was formed on the glass plate surface where micro pattern had been printed by commercial organic photoresist material. Then the resist material was dissolved off by acetone or ethanol with the TiO2 thin film just on. From SEM observation, it is indicated that micro pattern of TiO2 thin film transcribing the resist pattern with minimum line width of I νm was obtained. This method will be applicable to the construction of highly integrated dielectric devices.