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Advanced gas deposition was used to make nanocrystalline gold films.

A new study aims to produce high quality nanocrystalline particles showing a solid solution, focusing on the magnetic properties of Ag-Mn nanoparticles and demonstrating an unambiguous spin glass state.

A study was conducted to analyze the influence of a YBa2CU3O(sub 7-x) buffer layer on the quality of rf magnetron sputtered epitaxial (001) SrTiO3 thin films on a LaAlO3 substrate. High resolution transmission electron spectroscopy was utilized to carry out the analysis. The film was oriented with the (001) axis parallel to the normal of the substrate surface. Results indicated that rubbed polyimide alignment layers promoted a surface pretilt of 0.5 degrees.

A study demonstrated that electron energy-loss spectroscopy in transmission electron microscopy is a useful technique for analysis of the high-frequency dielectric properties on a microstructural level. Changes in the low frequency dielectric function between Sr deficient and stoichiometric films were much larger compared to the changes in the high-frequency function. It was found that strain and compositional deviations from the bulk value resulted in decreased ability to withstand dielectric breakdown.

High resolution analytical transmission electron microscopy was employed to determine the properties of the structural features of light emitting Si/SiO2 multilayers. Complex dielectric function was extracted from the experimental single-scattering distribution by utilizing the Kramers-Kronig analysis. This indicated the presence of an optical band gap at 1.5 eV. The first resonance peak in the imaginary portion of the complex dielectric constant was at 1.9 eV.

The influence of growth temperature from 170 to 730 deg C on the characteristics of as-deposited 1000 angstrom thick Ta2O5 films was investigated. The layers were grown through the evaporation of tantalum metal on silicon exposed to a flux of oxygen radicals. Films grown at or below 400 deg C were found to be deposited in an amorphous state. The layers grown at 520 deg C were found to be in a nanocrystalline state with no apparent grain boundaries while the films grown at 650 deg C had distinct grain boundary formation in the beta-phase modification of Ta2O5.

Research was conducted to characterize Sr-deficient and stoichiometric epitaxial (001) SrTiO3 films, deposited on (110)(sub rhombohedral) LaAlO3 substrates by x-ray diffraction and a high-resolution transmission electron microscopy. Objective of the study was to determine the reason for the significance of a heat treatment after deposition, tetragonal distortion and the influence of strain relaxation. Results indicate that the tetragonal distortion caused by the mismatch strain was concentrated to a narrow region closest to the film/substrate interface.

Investigation of tin oxide films doped with oxygen vacancies, molybdenum, tin or fluorine reveals that those films doped with tin or flourine or both possess the lowest value of resistivity and very high luminous transmittance. These films also have a low luminous absorptance value and infrared reflectance in the range of 70% to 90%. Hall effect analysis performed on these films indicates the existence of n-type conduction with very high electron densities. The properties of these films are permanent and are not affected by the passage of time.

The precursor oxide phases of pulsed laser deposited-YBCO films grown on (100)-oriented SrTiO3 substrates intermix to form a novel epitaxial solid-phase film. Epitaxial nucleation of the YBCO layers by the substrate interface is essential for solid-phase film formation. In situ resistance observations of the YBCO growth phase showed that interdiffusion occurs very quickly and immediately after production of ablated products from the initial precursor oxide layer.

In-plane orientation of the c-axis-oriented YBa2Cu3O(7-x) (YBCO) thin films prepared on (001) yttria-stabilized ZrO2(YSZ) substrates are sensitive to deposition properties resulting in mixed orientations. A dominant (110)(sub YBCO)/(110)(sub YSZ) orientation is detected at a deposition temperature of 770 degrees Celsius. The film microstructure on stepped substrate surfaces influence microwave surface resistance and contain superconducting properties.

Laser deposition methods yield YBa2Cu3O(7-X)/insulator/YBa2Cu3O(7-x) trilayers having one PrGaO3 layer and an SrTiO3 (STO)/PGO multilayer. Pinholes in PGO layers produce superconducting microshorts, and are eliminated by introducing thin STO films as buffer layers in the PGO.

The modified off-axis sputtering technique with high deposition rates is used to obtain high quality epitaxial YBa2Cu3O(sub 7-delta). The target-to-substrate separation influenced the deposition rate and film quality. Epitaxial YBCO/NdGaO3(NGO)/YBCO trilayers were grown onto SrTiO3, Y-ZrO2 and LaAl/O3 substrates by direct current and radio frequency sputtering. The top YBCO layers grew c axis oriented unaffected by the two epitaxial orientation of the NGO and the orientation relationships between YBCO/NGO were the same.

Y1Ba2Cu3Ox (YBCO) and Y-ZrO2 (YSZ) films were grown by pulsed layer deposition technique on sapphire substrates. It was observed that the c-axis oriented YBCO grows on amorphous YSZ at an optimal thickness of YSZ. An buffer layer of nine nanometers produced a Tc of 89 Kelvin which reflect the strong correlation of the properties of YBCO and the thickness of the buffer layer. The experiment further developed a model which showed the film growth process.

The interface between the Al bottom contact layer and Si substrates in Al based Josephson junctions is believed to have a significant effect on the noise observed in Al based superconducting devices. We have studied the atomic structure of it by transmission electron microscopy. An amorphous layer with a thickness of ∼5 nm was found between the bottom Al electrode and HF-treated Si substrate. It results from intermixing between Al, Si, and O. We also studied the chemical bonding states among the different species using energy loss near edge structure. The observations are of importance for the understanding of the origin of decoherence mechanisms in qubits based on these junctions. [ABSTRACT FROM AUTHOR]

The effect of growth conditions on the microstructure of BiFeO3-0.33BaTiO3 (BF-BT) films and the performance of bulk acoustic wave (BAW) resonators is analyzed using test structures with the BF-BT films grown at different positions relative to the plume axis in the pulsed laser deposition system. The BF-BT film grain size and surface roughness reveal a strong asymmetric surface distribution and decrease significantly in the film region facing the laser beam-plume interaction area. The (100) BF-BT texturing is enhanced in this film region. The variations in the BF-BT film microstructure result in corresponding variations of the BAW resonator performance. Their correlations are established using the model of the roughness induced attenuation of the reflected acoustic waves and theory of the dc field induced piezoelectric effect. The BAW resonators with the highest parameters are obtained in the BF-BT film region facing the laser beam-plume interaction area. The BAW resonators located in this film region reveal a mechanical Q-factor of 200 at 4.2 GHz, an effective electromechanical coupling coefficient of 10% and a tunability of the series resonance frequency of 4.5%. [ABSTRACT FROM AUTHOR]

An interaction layer is found at the Al/SiO2 interface in Al/AlOx/Al tunnel junctions grown on SiO2 substrates. The amorphous intermixing layer has an average thickness of about 5 nm. We present the detailed structure of this interfacial layer as determined by transmission electron microscopy. The layer contains alumina with aluminum being octahedrally coordinated according to electron energy loss spectroscopy analysis rather than tetrahedrally coordinated, where the latter coordination is the most common type in amorphous alumina. Depth profiles of the Al-O and Si-O bonding characteristics were also investigated using energy loss near edge structure. [ABSTRACT FROM AUTHOR]

Correlations between microstructure and Q-factor of tunable solidly mounted Ba0.25Sr0.75TiO3 (BSTO) thin film bulk acoustic wave resonators are studied using analysis of test structures prepared at different growth temperatures of the BSTO films varying in the range 450-650 °C. The observed changes in the Q-factor with growth temperature are correlated with related changes in microstructure, including the grain size, texture misalignment, interfacial amorphous layer, surface roughness, and deterioration of the Bragg reflector layers. The correlations are established through analysis of corresponding extrinsic acoustic loss mechanisms, including Rayleigh scattering at localized defects, acoustic attenuation by amorphous layer, generation of the shear waves leaking into the substrate, waves scattering by surface roughness, and resonance broadening by local thickness variations. It is shown that the waves scattering by surface roughness at the BSTO film interfaces is the main loss mechanism limiting the Q-factor of the BSTO thin film bulk acoustic wave resonators. [ABSTRACT FROM AUTHOR]

Tunable 5.2 GHz bulk acoustic wave resonators utilizing BaxSr1-xTiO3 ferroelectric films with similar intrinsic properties but different interface roughness are fabricated and characterized. Increase in roughness from 3.2 nm up to 6.9 nm results in reduction in Q-factor from 350 down to 150 due to extrinsic acoustic losses caused by wave scattering at reflections from rough interfaces and other mechanisms associated with roughness. The increased roughness is a result of distortion of Pt bottom electrode caused by formation of heterogeneous enclosures of TiO2-x in the Pt layer. [ABSTRACT FROM AUTHOR]

Current and voltage noise measurements have been carried out on nanoparticle WO[sub 3] films. The fluctuation dissipation theorem holds, which indicates that the observed noise is an equilibrium phenomenon. Results on the thinnest films show that noise measurements can be used for quality assessment of nanocrystalline insulating films. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Advanced gas deposition was used to produce nanocrystalline gold films under conditions giving four different deposition rates. Grain growth and structural modification of the grain boundaries were probed during annealing by use of in situ electrical transport measurements. Time dependent resistivity data were fitted to a relaxation model whose activation energy went up upon increased isothermal annealing temperature. The grain boundary transmission coefficient for the samples scaled, up to a certain limit, with the deposition rate; this is believed to be due to a higher concentration of pores, or a wider grain boundary region containing a disordered structure, in samples prepared at low deposition rates. Such samples also displayed enhanced thermal stability with negligible grain growth up to 773 K upon annealing in vacuum for 2 h. Samples prepared above this limit, at the highest deposition rate, exhibited a decreased grain boundary transmission coefficient. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Atomic force microscopy and transmission electron microscopy facilitated the study of the initial growth stages of YBa2Cu3O(7-delta) (YBCO) films that were grown on (001) Y-ZrO2 substrates using pulsed laser deposition. Initial growth stages include the formation of large CuO particles and a YBCO layer that was one unit cell thick.

A type of scanning microscope is described that has worked by directed imaging the electron field-emission sites on a nanotip. The advantages of the low energy, bright-beam electron microscope with atomic resolution are described and they are used for sequencing the human genome from a single strand DNA and for identifying atomic species directly from the elastic scattering of electrons.

Studies the influence of the substrate morphology in YBa[sub2]Cu[sub3]O[sub7-x] thin films on yttria-stabilized ZrO[sub2] substrates. Details on the experiment; Results of the study; Discussion of findings.

Deals with a study which investigated the development of interfacial microstructure during cooling of a zinc oxide varistor material from the sintering temperature through a combination of analytical electron microscopy and x-ray diffractometry. Information on zinc oxide varistor materials; Methodology of the study; Results and discussion.

Studies the effect of bismuth oxide content on the microstructure and electrical properties of zinc oxide varistor materials. Characteristics of zinc oxide varistor materials; Details on the experiment; Discussion on the results of the study.

Presents a study that investigated the role of different types of interfaces in a zinc oxide varistor material. Analysis of the current-voltage characteristics of the samples; Examination of the microstructure of the varistor; Evaluation of the voltage breakdown at different interfaces.

Describes the electromagnetic properties of YBa[sub2]Cu[sub3]O[sub7] (YBCO) step edge junctions and the microstructures of YBCO thin films grown on straight and wavy step edges on (001) LaAlO[sub3] (LAO) substrates. Information on the YBCO grain boundary; Factors to consider before growing a YBCO film; Technique used to study the microstructure of the YBCO film across the straight and wavy step edges on (001) LAO substrates.

Presents a study in which the epitaxial trilayer heterostructures of a combination of superconducting and ferrolectric materials were grown on silicon-on-sapphire buffered by a double layer of CeO[sub2]/Y-ZrO[sub2]. Information on the dielectric permittivity and the high frequency loss tan δ of the Ba[subx]Sr[sub1-x]TiO[sub3] layer; Experimental details; Superconductivity of the bottom YBCO layer.

Deals with a study which applied the pulsed laser deposition technique to study the process of layering and intermixing of precursor oxide phases of yttrium-barium[sub2]-copper[sub3]-oxide[sub7-δ] during deposition from separate component targets. Mechanism of the solid-phase epitaxial growth process; Grain-boundary diffusion model; Growth and characterization of films from component oxide targets.

Current and voltage noise measurements are carried out on nanaparticle WO3. Results on the thinnest films show that noise measurements can be used for quality assessment of nanocrystalline insulating films.

Provides information on a study which examined the growth of high quality superconducting films YBa[sub2]Cu[sub3]O[sub7-δ] on yttrium zirconium oxide substrates. Application of transmission electron microscopy; Results and discussion; Conclusions.