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The magnetic memory effect in GdBa2Cu3O7-x has been studied. By investigating the current–voltage characteristics, a voltage drop across the superconducting sample is observed on applying an external magnetic field. After the removal of the magnetic field, the voltage continues to decrease. This phenomenon is considered to be a nonvolatile memory effect. The voltage drop increases with applied magnetic flux, but it becomes constant at about 10 mT. The voltage drop is ascribed to the trapping of magnetic flux. While negative resistance occurs, the memorized state affects directly the magnitude of the differential voltage (ΔV), which is defined as the difference between threshold voltage and sustaining voltage. The mechanism of the memory effect and negative resistance can be sufficiently explained by the hypothesized macrostructure model of GdBa2Cu3O7-x superconducting ceramic materials.

Using only a simplified hot-filament chemical vapor deposition (SHFCVD) that has been improved and modified by drawing upon Matsumoto's hot-filament chemical vapor deposition (HFCVD) technique, the growth regions of carbonaceous product, such as carbon nanofibers or nanotubes and simple carbon films were examined consistently using of identical catalysts and carbon sources under different growth conditions. Ethanol (C2H5OH) and Ni metal were chosen and used as the carbon source and catalyst, respectively. This was considered to be the first examination, although other growth methods to synthesize carbonaceous products exist. Experimental results showed that the products could possibly be used to cover all grown regions by only changing substrate temperature (reaction temperature) and flow rate of hydrogen gas for bubbling in a carbon source. A comparison with products obtained using other equipment was performed.

The electron emission mechanism of a cathode covered with carbon-based hard film is discussed in relation to thermionic electron emission. This new model can reproduce the frequently observed peculiar Fowler-Nordheim plots consisted of two distinct parts, which are a strong electric field dependent part and a very weak field dependent part. It is shown that there is a relationship between the threshold electric field and film thickness as well as the threshold electric field and anode-cathode distance. The present model requires neither special field-enhancement mechanisms nor extremely small work function but does require retarding potential at dielectric-film/vacuum interface (∼1 eV).

Thermally induced coupling of gelation and phase separation in polysaccharide aqueous solutions has a complex feature because of critical and tricritical phenomena, thermally induced hydrophobic interaction, and molecular-weight distribution of the polysaccharide. To elucidate the process, the criticality of a hydroxypropylmethylcellulose (HPMC) aqueous solution was assessed, and then dielectric relaxation and fluorescence intensity experiments were carried out. The diffusion coefficient of the solution with a weight fraction of HPMC being 0.06 could be extrapolated to zero at the cloud-point curve which showed the criticality of the solution. The fluorescence intensity increased at a temperature much lower than the cloud point and the gel point, especially for concentrated solutions, indicating the hydrophobic interaction as the driving force of the gelation coupled by the phase separation. Dielectric relaxation measurements by time-domain reflectometry revealed two characteristic relaxations of chain motions around 100 MHz and orientation of free water around 20 GHz , which is accompanied by a low-frequency tail reflecting hydration water.

The electrolytic decomposition of an amaranth dyestuff solution using several combinations of electrodes with diamond and platinum is reported. It is observed that a portion of the amaranth is decomposed on the cathode surface while the other portion is decomposed to lower molecular weight components on the anode surface. The decolourizing rate is higher at diamond electrodes used as the anode and the cathode than with other combinations. This electrode combination also shows a rapid decrease in total organic carbon concentration. Acetic acid and oxalic acid are detected as the intermediate substances, and CO2 gas is generated as a final product corresponding to the decrease in the oxalic acid concentration.

Nitrogen-containing liquids N,N-dimethylformamide [HCON(CH3)2] and acrylonitrile (CH2CHCN) were selected as electrolytes in attempt to electrochemically deposit carbon nitride films on silicon substrates at atmospheric pressure and low temperature. The composition and bonding states in these films have been characterized by using X-ray photoelectron spectroscopy (XPS), Raman, and Fourier transform infrared (FTIR) measurements. It was evidenced that hydrogenated amorphous carbon nitride (α-CNx:H) films could be synthesized in acrylonitrile liquid, however, in N,N-dimethylformamide, only α-C:H:O films were obtained. These results indicate that electrodeposition of CNx films in the liquid phase is possible, and the selection of electrolytes and optimization of experimental parameters are the key factors in the liquid deposition process.

A new fabrication process of micromachines using anodic oxidized aluminium film has been developed. The aluminium oxide film was made by anodizing evaporated aluminium in H2SO4 solution with a constant voltage. For examples, a cantilever beams have been fabricated which is deflectable by electrostatics. And the Yong's modulus is determined from the resonance frequency of these beams, E=327GPa. From these results, we therefore conclude that anodic oxidized aluminium film is a good material of micromachines.

This paper is concerned with the mixing process of two dimensional confined laminar jet flow. In order to simulate these phenomena, numerical calculation and visualization experiment by Hydrogen Bubble Method are done. As a result, are made clear size, location and shape of the recirculation zone for effect of flow rate, nozzle-throat ratio and Reynolds number.

The current-voltage (I–V) characteristics and the contact resistance Rc of Au/, Al/ and Mg/chemically vapour deposited semiconducting diamond contacts were measured. The I–V characteristics of Al/ and Mg/p-diamond contacts changed their properties from an ohmic to a rectifying nature as the resistivity of the semiconducting diamonds increased, while the Au/p-diamond contact was ohmic. An Rc of less than 103 Ω cm2 is found to be necessary to obtain the ohmic contacts on semiconducting diamonds regardless of the metal. The rough estimate of the barrier height oB was also discussed using the results of the Rc measurement.

Semiconducting diamond films were deposited by the conventional hot filament chemical vapour deposition technique. Boron trioxide and diphosphorus pentaoxide have been used as the dopants for p- and n-type films respectively. The films obtained were identified as diamond by means of scanning electron microscopy, electron diffraction and Raman spectroscopy. The impurity concentrations in the films were evaluated using secondary ion mass spectroscopy. The semiconducting properties of the films were confirmed by measuring the resistivity, the Hall effect and the activation energy of the conductivity.

Current-voltage (I-V), capacitance-voltage (C-V) and isothermal capacitance transient spectroscopy (ICTS) measurements have been performed on p-n heterojunctions between B-doped polycrystalline diamond and P-doped hydrogenated amorphous silicon. The I-V characteristics of the heterojunctions show good rectification and the C-V characteristics show an approximate linear C−2-V relationship in the reverse-bias condition. From the ICTS results, it is found that one deep level in B-doped polycrystalline diamond is located at around 0.6 eV above the valence band edge. The density and the capture cross-section of the deep level were determined to be 2 × 1016 cm−3 and 1 × 10−17 cm2 respectively.

In this study, the fishing effect observed in a Bi-based BiPbSrCaCuO (BPSCCO) superconductor was investigated. The electromagnetic properties of a silver-oxide (Ag2O) doped BPSCCO superconductor and an undoped superconductor were evaluated to investigate the contribution of the pinning centers to the fishing effect. It was confirmed experimentally that a large amount of magnetic flux was trapped in the Ag2O doped sample than that in the undoped one, indicating that the pinning centers of magnetic flux are related closely to the occurrence mechanism of the fishing effect. It is considered that by adding Ag2O, the area where normal conduction takes place increases and the magnetic flux penetrating through the sample increases. It also is considered that Ag2O acts to increase pinning centers of magnetic flux, contributing to the occurrence of the fishing effect. The occurrence mechanism of the fishing effect can be explained by a qualitative model based on the relationship between the pinning centers and the distribution of the lines of magnetic force caused by a toroidal permanent magnet.

High-quality diamond particles up to 0.6 mm in diameter were produced by are discharge plasma chemical vapor deposition. An ethanol-methanol-hydrogen gas mixture at pressures ranging between 250 and 400 torr was used as a reactant gas. The particles were formed by spontaneous nucleation on a molybdenum substrate and grown within a few hours at substrate temperatures as high as 1300 °C. Growth rates in the range 0.1–0.3 mm/h were common. Three experimental techniques aimed at reducing the number of spontaneously formed diamond nuclei were attempted and found feasible. Nuclei density as low as 10 cm −2 were achieved.

A diamond p-n junction diode has been fabricated by the chemical vapour deposition technique. Diphosphorus pentaoxide and boron trioxide were used for the doping sources for the n- and p-type diamond films respectively. The films were identified as diamond from the results of the electron diffraction and Raman spectroscopy. The diode exhibited distinct rectification characteristics. The formation of the depletion layer was confirmed from the result of the electron-beam-induced current measurement.

A transient negative photoconductivity phenomenon observed in silicon doped with gold atoms has been investigated. On the basis of the trapping of photo-excited carriers into two deep levels of gold atoms, a model for the occurrence of transient negative photoconductivity is proposed and related qualitatively to some experimental results.

Electron field emission has been studied with diamond-like carbon (DLC) films deposited from a liquid phase. The DLC films were deposited on Si substrate by electrolysis of methanol liquid. The field emission measurements were carried out with a parallel plate configuration using the deposited DLC films on Si substrate as a cathode, and an indium tin oxide (ITO) coated glass plate as an anode. We found several bright spots on a luminescent screen mounted on the ITO anode, indicating that the electrons are emitted from the isolated emission sites on the deposited DLC film. The emission current density is more than 10−7 A/cm2 at the electric field as low as 1.2 V/μm. This result suggests that the DLC film deposited from the liquid phase has a potential advantage for field emitter applications.

The magnetic susceptibilities of liquid CrTe, MnTe and FeTe alloys decrease with increasing temperature. The effective Bohr magneton numbers P obtained from the Curie-Weiss law are about 4.31, 5.53 and 4.42 for liquid CrTe, MnTe and FeTe, respectively. The large values of P suggest that the d-states of Cr, Mn and Fe ions in these liquid alloys are split into two sub bands of spin up and spin down due to the intra-atomic Coulomb interaction. The susceptibilities of liquid TiTe, VTe, CoTe and NiTe alloys show non-magnetic behaviour. However, those of liquid VTe and CoTe alloys become magnetic on increasing the concentration of the transition metal. The density of d-states at the Fermi level can be estimated from the susceptibilities of transition metal alloys for a non-magnetic state. These results are consistent with the trend of the electrical conductivities of liquid transition metal-Te alloys.

Boron-doped diamond films have been synthesized by the thermal filament CVD method. As the doping source, boron trioxide powder was used instead of diborane. The films obtained were identified as diamond by several methods including Raman spectroscopy. The resistivity of the films was inversely proportional to the doping concentration over four order. p-Type electrical conduction was also confirmed by measuring the Seebeck effect.

Electrochemical deposition of amorphous carbon (a-C) film is performed by applying a direct-current potential to substrates immersed in methanol. Both scanning electron microscopy and Raman results indicate that smooth and homogeneous a-C films are grown on specific substrate materials such as Si, Ti, and Al. Field emission measurements demonstrate excellent emission properties such as threshold fields lower than 5 V/μm. Field enhancement factors are estimated to be 1300–1500; these are attributed to local field enhancements around sp2 carbon clusters that are embedded in the a-C films. Emission properties of a-C films grown on Si exhibit a current saturation under higher applied fields. These saturation behaviors are explained by an effect of a potential barrier formed at the interface between a-C films and substrates. Since the interface barrier is reduced by formation of the Ti interfacial layer, an approach to use carbide formation at the interface is verified as useful to improve the emission properties of a-C films.

Characteristics of Schottky barriers formed on homoepitaxial diamond film have been studied. Current–voltage characteristics of Al contacts on both the as‐grown film and the oxidized film show rectification. On the other hand, ohmic property is observed on Au/as‐grown film while Au/oxidized film shows rectification. These results imply that the mechanism of the barrier formation on the as‐grown diamond is drastically changed by oxidation. The difference of electrical properties between the as‐grown film and the oxidized film is also observed from capacitance–voltage characteristics. This result suggests that additional acceptors which are not related to boron, exist in the as‐grown film and disappear after oxidation.

A diamond field emitter array has been fabricated. by Chemical vapor deposition. Diamond was grown on an inverted pyramidal‐shape Si substrate followed by removal of the substrate. The fabricated array was placed in a high vacuum pumping system with the pressure of ∼10−7 Torr and the emission current as a function of the anode voltage was measured. The distance between the tungsten anode and the diamond surface was held constant at 100 μm throughout the measurement. As a result, a current larger than 10−4 A was obtained for an anode voltage of 6 kV. A linear relationship in the Fowler–Nordheim plot indicated the existence of electron field emission from the fabricated diamond field emitter array.

A deep level in boron‐doped polycrystalline diamond films located approximately 0.6 eV above the valence‐band edge has been found using isothermal capacitance transient spectroscopy (ICTS) measurements. p‐n heterojunctions between polycrystalline diamond and hydrogenated amorphous silicon were used in the study. The density and the hole‐capture cross section of the deep level traps were determined from the temperature dependence of ICTS spectra and found to be 2×1016 cm−3 and 1×10−17 cm2, respectively.

The molecular beam epitaxial growth processes of Al single‐crystal layers deposited at room temperature on As‐stabilized and on Al‐stabilized AlAs surfaces are investigated in situ using reflection high‐energy electron diffraction (RHEED). The epitaxy relationship of Al with the underlying AlAs is (011)[100]Al//(001)[110]AlAs irrespective of the surface stoichiometry of AlAs. Detailed RHEED investigation suggests that the initially deposited two one‐monolayer‐thick Al layers form a sphalerite lattice on As‐(Al‐)stabilized AlAs with the same lattice spacing as AlAs, while the deposition of additional Al layers induces the structural phase transition from the sphalerite lattice to an fcc lattice with bulk Al lattice constant. Thick epitaxial Al layers show (4×1) surface reconstruction.

A diamond p − n junction diode has been fabricated by the chemical vapour deposition technique. Diphosphorus pentaoxide and boron trioxide were used for the doping sources for the n - and p -type layers, respectively. The diode shows distinct rectification characteristics at 300 K room temperature. This diode shows rectification even at 370 K and this result implies the possible use of diamond as a semiconductor in high temperature conditions.

An n-type semiconducting diamond film has been synthesized by the hot filament CVD method using diphosphorus pentaoxide as the doping source. The obtained film was identified as polycrystalline diamond containing few sp2 components by means of several methods including Raman spectroscopy. From measurements of the Hall effect and the Seebeck effect, the film was found to be an n-type semiconductor.

Boron-doped diamond films were deposited onto (100) orientated Si substrates using a thermal filament CVD method. Boron trioxide was used as a doping source and samples with boron to carbon ( B C ) ratios of 0, 10, 100 and 1000 ppm were prepared for the Raman and infrared (ir) spectroscopy studies. The ir results s show that thin layers of SiC are formed at the interface. Furthermore, the ir data confirm the resistivity data obtained from electrical measurements. Raman spectroscopy was used to probe the quality and homogeneity of the diamond films. In addition, the optical absorption was found to increase strongly with increasing B C ratio.

Electrical properties of polycrystalline diamond / hydrogenated amorphous Si interfaces have been studied in order to clarify the effect of the morphology of the polycrystalline diamond films on the electrical properties of these materials. From I-V and C-V characteristics, the depletion layer occurs in the vicinity of the junction in the same manner as for the conventional crystalline heterojunction. The temperature dependence of I-V characteristics are described by the conventional heterojunction models proposed for the crystalline semiconductors. It is also found that capacitance transients of the present heterojunctions can be observed, namely, measurements of isothermal capacitance transient spectroscopy (ICTS) can be performed. From the ICTS spectra, we have succeeded to get information of localized states in polycrystalline diamond and the interface states in the vicinity of the heterojunction.

Boron doped diamond films were deposited onto (100) orientated Si substrates using a thermal filament CVD method. Boron trioxide was used as a doping source and samples with boron to carbon (B/C) ratios of 0, 10, 100, and 1000 ppm were prepared for the optical measurements. The infrared (IR) results reveal the formation of an ultrathin SiC layer at the interface between Si and diamond. Furthermore, the IR data confirm the resistivity data obtained from electrical measurements. Raman spectroscopy was used to probe the quality and homogeneity of the diamond films. Upon increasing B/C ratio the diamond phonon line shifts to lower frequency and is also broadened revealing a softening of the diamond. In addition, the optical absorption was found to increase strongly with increasing B/c ratio.

Experimentally obtained results of the change in electrical resistance of the p-type diamond surface conductive layer (PSCL) are simulated using a rate equation. According to a model that simulates the process responsible for the decrease in electrical resistance caused by acid mist containing oxonium ions (H3O+), H3O+ ions react with hydrogen atoms terminating dangling bonds on the diamond surface and cause the creation of holes in diamond films. The rate equation describing these hole creation processes is set up and time-dependent electrical resistance is simulated. The simulated results are in agreement with the experimental results.

Diamond-like carbon (DLC) films were synthesized by an electrodeposition technique on silicon (Si) substrates using liquid N,N-dimethylformamid (DMF). The electrodeposition was performed in the temperature range from 40 to 80°C and the applied voltage range from -1 kV to -5 kV. The structures of the films were characterized by Raman spectroscopy. The films with the electrical resistivity of about 1010 Ω·cm can be deposited using the liquid DMF under the liquid temperature of 80°C and the applied voltage of -2 kV. Moreover, the current density has an important role in the deposition of the films.