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This study uses radio-frequency sputtering methods to deposit lead titanate thin films with different contents of Ca on Pt/Ti/SiO2/Si substrates to form Pb1-xCaxTiO3 (PCT) thin films. The PCT thin films contained different amounts of Ca in order to examine the influence of the Ca content on the properties of thin films. Analysis of the electrical properties of the PCT thin films revealed that their relative permittivities, dissipation factors, and pyroelectric coefficients tend to increase with the Ca content. On the other hand, the coercive field and remnant polarization decreased with an increase in the Ca content. In addition, the measured data indicated that the figure of merit for voltage (Fv) and the figure of merit for detectivity (FD) of a PCT (30) thin film are the highest with values of 0.033 m2 C-1 and 0.862×10-6 (m3 J-1)1/2, respectively. Therefore, the PCT (30) thin film was evaluated as the best composition for manufacturing pyroelectric infrared (PIR) sensors. PCT thin films were also used to fabricate thermal PIR sensors by surface machining technology. The detectivity measurement showed that the PIR sensor with PCT (30) thin films has the highest value of D* (1.29×107 cm Hz1/2/W) at 0.3 Hz. [ABSTRACT FROM AUTHOR]

Studies the surface layers on superconducting thin films using an x-ray photoelectron spectroscopy. Importance of x-ray photoelectron spectroscopy; Overview on the experiment; Discussion on the result of the study.

Discusses the preparation of superconducting thin films of y[sub1]-Ba[sub2]-Cu[sub3]-O[subx] with superconducting temperature and prepared by a laser deposition technique. Method used in film preparation; Effects of thermal stresses in the films; Composition of the film; Result of the x-ray powder diffraction of the films.

Magnetic properties of microstructured Permalloy thin film cross have been studied using magnetic force microscopy and magnetoresistance measurement. Three types of magnetization configurations formed within the junction area were observed, including two kinds of magnetic pattern having two inward and two outward magnetizations and one with three outward and one inward magnetizations. The presence of those variant magnetic configurations gives rise to an irreversible magnetoresistance behavior originated from the distinct magnetization history. Asynchronous magnetization reversal of each arm provides a chance to manipulate the magnetic pattern of the cross. [ABSTRACT FROM AUTHOR]

This study takes the first step in designing ZnO thin film pressure sensors with high operating temperatures. To fabricate the pressure sensors, ZnO thin films are deposited on SiO[sub 2]/(100)Si substrates to obtain structures similar to those of silicon-on-insulator. The optimal deposition parameters used to deposit the thin films are a full width at half maximum (FWHM) of 0.269, a c-axis-oriented structure near 100% and an average grain size of 321 Å. Here, to simplify the ZnO thin film pressure sensor system, a new parameter, the ZnO resistance, which changes with the change of pressure, is analysed. ZnO thin film fabricated under the optimal conditions can work as a pressure sensor and its response value, which is proportional to pressure, is greater than 8 mω/psi. The relative pressure can be obtained from the difference between the response value before applying pressure and after. Further, a special characteristic of these ZnO pressure sensors is that the pressure can be read even during gas inlet. [ABSTRACT FROM AUTHOR]

For crystalline advanced materials, such as the high transition temperature oxide superconductors, the growth of defect-free crystals is often the most sought after desideratum because it opens the doors to fundamental studies and the development of practical applications. We report the observation of YBa2Cu3O7-x(123) thin films having unprecedented structural perfection, at temperatures near 700 °C on [001] LaAlO3. The film’s c axis is in the surface plane, unlike films grown at higher temperatures. This orientation has important advantages for device applications and fundamental studies. The Tc,0 is only 70 K, presumably due to oxygen deficiency caused by thermal stresses; if so, it should be possible to raise the Tc,0 by relieving these stresses. [ABSTRACT FROM AUTHOR]

Superconducting Y1Ba2Cu3Ox films 300 nm thick with local surface roughness <5 nm have been prepared by laser deposition at 650 °C and subsequent heat treatments at 450 °C; highest zero resistance temperature was above 85 K. Smooth topography and low-temperature processing are crucial for device fabrication. These films are crack-free and density of particles with >1 μm diameter was <10/cm2. We suggest that an effective increase in surface temperature and deposition directly in the orthorhombic phase contributes to film quality. [ABSTRACT FROM AUTHOR]

Three previously unreported ternary phases of the type NixInP have been observed to be the primary reaction products of the Ni/InP reaction. The first phase, amorphous NixInP(x[bar_over_tilde:_approx._equal_to]2.7), forms at the Ni/InP interface by a solid-state amorphization process at low temperatures (T≲200 °C). Amorphous NixInP crystallizes at ∼300 °C to form a hexagonal NixInP phase (a0=0.412 nm and c0=0.483 nm) with a similar composition. A third ternary phase with nominal composition Ni2InP (monoclinic, a0=0.681 nm, b0=0.529 nm, c0=1.280 nm, and β=95°) nucleates at higher temperatures and is the final reaction product. This final phase is stable at temperatures up to 500 °C in samples capped with SiO2. [ABSTRACT FROM AUTHOR]

Positive and negative lithographic patterns have been produced in epitaxial layers of GaAs, achieved by electron beam writing and subsequent etching by Cl2 gas at elevated temperatures. A latent image is formed in the native oxide which is either less resistant to thermal Cl2 etching (positive pattern) or more resistant to thermal Cl2 etching (negative pattern), depending on the electron beam dose. The pattern is stable in air for at least several weeks. The tone of the pattern also depends on the electron beam accelerating voltage, the etching conditions, and the thickness and initial state of the native oxide. Significant changes in the resulting lithography are due to changes in an oxide only a few monolayers thick. Both positive and negative patterns can be produced in adjacent areas with high contrast by variation of the electron-beam does. Initial Auger analysis suggests that chemical rearrangement of the native oxide occurs with electron beam exposure. The discovery that the native oxide on GaAs acts as both positive and negative resists opens tremendous possibilities for in situ processing and device fabrication. [ABSTRACT FROM AUTHOR]

Critical current densities (Jc) in YBa2Cu3O7-x films made at deposition rates from 0.1 to 14.5 nm/s (∼50 μm/h) were measured using a direct transport method. As the deposition rate was increased by two orders of magnitude, the films exhibited no marked degradation in current carrying capability with Jc of ∼4×106 A/cm2 at 77 K and zero field. Jc for all the films showed similar behavior under a magnetic field up to 8 T, although extra structural defects were found in the films deposited at the higher rates. The results from this experiment indicate the feasibility for coating wires, tapes, and other macroscopic shapes with high Tc superconductors using proper vapor deposition techniques. [ABSTRACT FROM AUTHOR]

We have investigated the transport current-induced resistive transitions in predominantly c-axis oriented crystalline Y1Ba2Cu3O7-x superconducting thin films with scanning electron microscopic (SEM) imaging and its correlation with dc current-voltage (I-V) measurements. We find that there is a nonlinear gradual transition region in the I-V curves that is caused by macroscopic effects (current ‘‘crowding’’, substrate defects, film thickness variation, etc.) and by microscopic dissipation effects. At a high current there is an abrupt transition to the normal state in the I-V curve due to Joule heating. The SEM mapping provides a direct image of the above effects and is useful for characterization and study of fundamental transport properties of high Tc thin films. [ABSTRACT FROM AUTHOR]

The microstructure of in situ epitaxially grown Y-Ba-Cu-O thin films on (001) SrTiO3 substrates was studied using cross-sectional transmission electron microscopy. The films, prepared by pulsed laser deposition at substrate holder temperature of 650 °C without post-annealing, exhibit zero resistivity above 90 K and critical currents exceeding 106 A/cm2 at 77 K. The films are of heavily faulted single crystalline structure with the c axis approximately perpendicular to the substrate (001) surface. We suggest that, due to the fast quenching and low substrate temperature, crystalline defects and chemical fluctuations are locked into a faulted structure after each laser pulse. Despite their rather imperfect microstructure, the films are free from macroscopic grain boundaries and secondary phases and possess superb superconducting properties. [ABSTRACT FROM AUTHOR]

As-deposited superconducting thin films (∼0.1 μm) of YBa2Cu3O7-x have been prepared by pulsed laser deposition on (100) Si with buffer layers of BaTiO3/MgAl2O4. X-ray diffraction studies reveal that the films grow epitaxially with the c axis preferentially oriented normal to the substrate surface. This is confirmed by ion channeling measurements along the (100) (normal to the surface) and (110) directions of the Si substrate showing a minimum yield of 54% along the (100), and 78% along the (110) axes using 2.8 MeV He++. Preliminary transmission electron microscopy study also supports these results. The as-deposited films have zero resistance temperatures of 86–87 K, and critical current densities of 6×104 A/cm2 at 77 K and 1.2×105 A/cm2 at 73 K. Our results indicate that the superconducting properties of the films are limited primarily by the quality and degree of epitaxal growth of the buffer layers on the silicon substrate. [ABSTRACT FROM AUTHOR]

We have grown ultrathin films of Y1Ba2Cu3O7-x in situ on (001) SrTiO3 by pulsed laser deposition. The zero resistance transition temperature (Tc0) is >90 K for films >300 Å thick. The critical current density (Jc at 77 K) is 0.8×106 A/cm2 for a 300 Å film and 4–5×106 A/cm2 for a 1000 Å film. The Tc0 and Jc deteriorate rapidly below 300 Å, reaching values of 82 K and 300 A/cm2 at 77 K, respectively, for a 100 Å film. Films only 50 Å thick exhibit metallic behavior and possible evidence of superconductivity without showing zero resistance to 10 K. These results are understood on the basis of the defects formed at the film-substrate interface, the density of which rapidly decreases over a thickness of 100 Å. We have studied these defects by ion channeling measurements and cross-section transmission electron microscopy. Our results suggest that the superconducting transport in these films is likely to be two dimensional in nature, consistent with the short coherence length along the c axis of the crystals. [ABSTRACT FROM AUTHOR]

High oxygen partial pressure has been found to be an important parameter for the pulsed laser deposition of as-deposited superconducting thin films with high Tc and Jc. The optical emissions from both elemental and oxide species ejected from the target of YBa2Cu3O7-x during the pulsed laser deposition process increase with the oxygen pressure, with the oxide emission showing a stronger pressure dependence than the elemental emission. The dynamics of the interaction between the oxygen atoms and the species in the laser-produced plume were studied by a wavelength and time-resolved measurement. The results are qualitatively explained using a simple model based on optical emission arising from inelastic and recombination collision between the elemental species and electronically excited oxygen atoms. The formation of oxides in the plume is shown to be essential for the production of higher quality superconducting films, indicating the value of optical spectroscopy as a diagnostic tool. [ABSTRACT FROM AUTHOR]

2000 Å as-deposited high Tc superconducting Y1Ba2Cu3O7-x films with zero-resistance temperatures of ∼89 K and critical current densities about 0.7×106 A/cm2 at 77 K have been reproducibly fabricated at a substrate holder temperature of 650 °C, using pulsed laser deposition, with no post-annealing. One key to these results is the injection of gaseous oxygen into the laser-produced plume just in front of the target. In this way, the correct amount of oxygen is incorporated into the as-grown film so that post-deposition treatment becomes unnecessary. The in situ growth of such high Tc and Jc films is an important step in the use of the laser deposition technique to fabricate multilayer structures such as Josephson junctions. [ABSTRACT FROM AUTHOR]

By depositing YBaCuO films at low substrate holder temperatures (600 °C) using a pulsed laser, films with the orthorhombic phase exhibiting superconductivity with high zero resistance temperatures (Tc0) were produced. Tc0 values as high as 50 and 80 K were seen on films deposited directly on Si and on Si with only a 50 nm ZrO2 buffer layer, respectively. The key to the successful film deposition is the low processing temperatures involved, which minimized the interface reactions as observed by Auger electron spectrometry. [ABSTRACT FROM AUTHOR]

Thin superconducting films of Y-Ba-Cu-O were prepared at 650 °C using the pulsed laser deposition technique. The as-deposited films were fully superconducting at low temperature (30 K). After annealing in oxygen at 450 °C for 3 h, the films exhibited superconductivity with zero resistance at temperatures as high as 83 K. Film-substrate interface reaction was minimal as revealed by Rutherford backscattering and Auger electron spectrometry. These films processed at such low temperatures are also found to have excellent planar surface morphology and high critical current density. [ABSTRACT FROM AUTHOR]

Etching of Y-Ba-Cu-O superconducting thin films has been accomplished using a pulsed excimer laser (248 nm, 30 ns). Etch depth as a function of the number of laser pulses was linear over a wide range of incident laser energy densities. An etch threshold energy density of 0.11 J/cm2 was observed and etch rate per pulse scaled linearly with the logarithm of the incident energy density. The dependence is adequately explained by a linear absorption model with an inverse absorption length of 2.3×105 cm-1. [ABSTRACT FROM AUTHOR]