Showing papers on "Electric field published in 1998"
01 Mar 1998
TL;DR: The quantum-confined Stark effect in single cadmium selenide (CdSe) nanocrystallite quantum dots was studied, suggesting the potential use of these dots in electro-optic modulation devices.
Abstract: The quantum-confined Stark effect in single cadmium selenide (CdSe) nanocrystallite quantum dots was studied. The electric field dependence of the single-dot spectrum is characterized by a highly polarizable excited state (∼10 5 cubic angstroms, compared to typical molecular values of order 10 to 100 cubic angstroms), in the presence of randomly oriented local electric fields that change over time. These local fields result in spontaneous spectral diffusion and contribute to ensemble inhomogeneous broadening. Stark shifts of the lowest excited state more than two orders of magnitude larger than the linewidth were observed, suggesting the potential use of these dots in electro-optic modulation devices.
696 citations
TL;DR: In this paper, three methods of detecting micromotion of ions in Paul traps have been described, including the change of the average ion position as the trap potentials are changed, and the amplitude of the sidebands of a narrow atomic transition, caused by the first-order Doppler shift due to the ion's ion motion.
Abstract: Micromotion of ions in Paul traps has several adverse effects, including alterations of atomic transition line shapes, significant second-order Doppler shifts in high-accuracy studies, and limited confinement time in the absence of cooling. The ac electric field that causes the micromotion may also induce significant Stark shifts in atomic transitions. We describe three methods of detecting micromotion. The first relies on the change of the average ion position as the trap potentials are changed. The second monitors the amplitude of the sidebands of a narrow atomic transition, caused by the first-order Doppler shift due to the micromotion. The last technique detects the Doppler shift induced modulation of the fluorescence rate of a broad atomic transition. We discuss the detection sensitivity of each method to Doppler and Stark shifts, and show experimental results using the last technique.
672 citations
TL;DR: In this article, a nematic liquid crystal cell associated with a homogeneously aligned to twisted transition of a liquid crystal director was fabricated, which exhibits a high transmittance ratio as well as a wide viewing angle.
Abstract: We have fabricated a nematic liquid crystal cell associated with a homogeneously aligned to twisted transition of a liquid crystal director. In the absence of an electric field, the liquid crystal molecule is homogeneously aligned under the crossed polarizers, and thus the cell appears to be black. When a fringe field induced by interdigital electrodes is applied, liquid crystal molecules rotate in plane even above electrodes and thus the cell transmits light. The device exhibits a high transmittance ratio as well as a wide viewing angle, which solves a long standing problem of low transmittance existing in the conventional in-plane switching mode. We show that the distance between electrodes smaller than the width of an electrode and cell gap is required for generating fringe field with applied voltage and rotating molecules above electrodes. We also investigate the mechanism of fringe-field switching and dependence of electro-optic effect on different cell conditions and dielectric anisotropy of liquid ...
656 citations
TL;DR: In this paper, the authors report observations of fast solitary waves that are ubiquitous in downward current regions of the mid-altitude auroral zone and propose that these nonlinear structures play a key role in supporting parallel electric fields.
Abstract: We report observations of “fast solitary waves” that are ubiquitous in downward current regions of the mid-altitude auroral zone. The single-period structures have large amplitudes (up to 2.5 V/m), travel much faster than the ion acoustic speed, carry substantial potentials (up to ∼100 Volts), and are associated with strong modulations of energetic electron fluxes. The amplitude and speed of the structures distinguishes them from ion-acoustic solitary waves or weak double layers. The electromagnetic signature appears to be that of an positive charge (electron hole) traveling anti-earthward. We present evidence that the structures are in or near regions of magnetic-field-aligned electric fields and propose that these nonlinear structures play a key role in supporting parallel electric fields in the downward current region of the auroral zone.
531 citations
TL;DR: The rotational excitation of small interstellar grains and the resulting electric dipole radiation from spinning dust was discussed in this paper, where the authors discussed the excitation and damping of grain rotation by collisions with neutrals, collisions with ions, plasmas drag, and formation of H2 on the grain surface.
Abstract: We discuss the rotational excitation of small interstellar grains and the resulting electric dipole radiation from spinning dust Attention is given to excitation and damping of grain rotation by collisions with neutrals, collisions with ions, "plasma drag," emission of infrared radiation, emission of electric dipole radiation, photoelectric emission, and formation of H2 on the grain surface Electrostatic "focusing" can substantially enhance the rate of rotational excitation of grains colliding with ions Under some conditions, "plasma drag"—due to interaction of the electric dipole moment of the grain with the electric field produced by passing ions—dominates both rotational damping and rotational excitation Emissivities are estimated for dust in different phases of the interstellar medium, including diffuse H I clouds, warm H I, low-density photoionized gas, and cold molecular gas Spinning dust grains could explain much, and perhaps all, of the 14-50 GHz background component recently observed by Kogut et al, de Oliveira-Costa et al, and Leitch et al Future sensitive measurements of angular structure in the microwave sky brightness from the ground and from space should detect this emission from high-latitude H I clouds It should be possible to detect rotational emission from small grains by ground-based pointed observations of molecular clouds, unless these grains are less abundant there than is currently believed
505 citations
TL;DR: In this paper, a model for the formation of holographic surface relief gratings in azobenzene functionalized polymers is presented, where forces leading to migration of polymer chains upon exposure to light in the absorption band of the azo chromophore are attributed to dipoles interacting with the gradient of the electric field present in the polymer material.
Abstract: A model for the formation of holographic surface relief gratings in azobenzene functionalized polymers is presented. Forces leading to migration of polymer chains upon exposure to light in the absorption band of the azo chromophore are attributed to dipoles interacting with the gradient of the electric field present in the polymer material. Efficient trans–cis cycling in the azobenzenes allows cooperative movement of the chromophores under the influence of gradient forces.
471 citations
TL;DR: In this paper, the underlying physics behind the success of the thermochemical E model in describing time-dependent dielectric breakdown (TDDB) in SiO2 thin films is presented.
Abstract: The underlying physics behind the success of the thermochemical E model in describing time-dependent dielectric breakdown (TDDB) in SiO2 thin films is presented. Weak bonding states can be broken by thermal means due to the strong dipolar coupling of intrinsic defect states with the local electric field in the dielectric. This dipole-field coupling serves to lower the activation energy required for thermal bond-breakage and accelerates the dielectric degradation process. A temperature-independent field acceleration parameter γ and a field-independent activation energy ΔH can result when different types of disturbed bonding states are mixed during TDDB testing of SiO2 thin films. While γ for each defect type alone has the expected 1/T dependence and ΔH shows a linear decrease with electric field, a nearly temperature-independent γ and a field-independent ΔH can result when two or more types of disturbed bonding states are mixed. The good agreement between long-term TDDB data and the thermochemical model su...
438 citations
TL;DR: In this paper, a review of sporadic E and related processes is performed as functions of viewing system, latitude and altitude, and it is shown that the windshear theory and the external electric field are sufficient along with the tidal wind system to explain the mid-latitude layers which are referred to as tidal ion layers (TILs) that have often been identified as sporadic E or as sequential sporadic E.
419 citations
TL;DR: The POLAR plasma wave instrument often detects coherent electric field structures in the high altitude polar magnetosphere, which are found to move both up and down the ambient magnetic field as mentioned in this paper.
Abstract: The POLAR plasma wave instrument often detects coherent electric field structures in the high altitude polar magnetosphere. The structures appear to be positively charged potentials which are found to move both up and down the ambient magnetic field. Typical estimated velocities and parallel scale sizes are the order of 1000 km/s and 100-1000 meters, respectively. We have observed the structures at radial distances of 2.02 to 8.5 Re and L shells of 6 - 12+, although the they are likely to occur over a broader range of space than suggested by this initial study. The structures are responsible for some of the the spectral features of broadband electrostatic noise, and are similar to recent GEOTAIL and FAST observations of solitary waves.
351 citations
TL;DR: In this article, a nonstandard evaluation of band offsets and formation energies of wurtzite III-V nitrides was performed, and it was shown that large uniform electric fields exist in epitaxial nitride overlayers.
Abstract: Ab initio electronic structure studies of prototypical polar interfaces of wurtzite III-V nitrides show that large uniform electric fields exist in epitaxial nitride overlayers, due to the discontinuity across the interface of the macroscopic polarization of the constituent materials. Polarization fields require a nonstandard evaluation of band offsets and formation energies: we find a large strain-induced asymmetry of the offset [0.2 eV for AlN/GaN (0001), 0.85 eV for GaN/AlN (0001)], and tiny interface formation energies.
344 citations
TL;DR: In this article, an analytic theory for dark injection from a metallic electrode into a random hopping system, e.g., a conjugated polymer or a molecularly doped polymer, is presented.
Abstract: An analytic theory is presented for dark injection from a metallic electrode into a random hopping system, e.g., a conjugated polymer or a molecularly doped polymer. It encompasses injection of a charge carrier from the Fermi level of the electrode into tail states of the distribution of hopping states of the dielectric followed by either return of the charge carrier to the electrode or diffusive escape from the attractive image potential. The latter process resembles Onsager-type geminate pair dissociation in one dimension. The theory yields the injection current as a function of electric field, temperature and energetic width of the distribution of hopping states. At high electric fields it resembles that the current calculated from Fowler-Nordheim tunneling theory although tunneling transitions are not included in the theory. Good agreement with experimental data obtained for diode structures with conjugated polymers as a dielectric is found.
TL;DR: In this paper, the authors present observations of intense, bipolar, electrostatic structures in the transition region of the terrestrial bow shock from the Wind spacecraft and interpret the observations as small scale convecting unipolar potential structures, consistent with simulations of electron phase space holes.
Abstract: We present observations of intense, bipolar, electrostatic structures in the transition region of the terrestrial bow shock from the Wind spacecraft. The electric field signatures are on the order of a tenth of a millisecond in duration and greater than 100 mV/m in amplitude. The measured electric field is generally larger on the smaller dipole antenna, indicating a small spatial size. We compare the potential on the two dipole antennas with a model of antenna response to a Gaussian potential profile. This result agrees with a spatial scale determined by convection and gives a characteristic scale size of 2–7 λd. We interpret the observations as small scale convecting unipolar potential structures, consistent with simulations of electron phase space holes and discuss the results in the context of electron thermalization at strong collisionless shocks.
TL;DR: Alkanethiol self-assembled monolayers (SAMs) on a mercury surface are used to build a junction consisting of two opposing mercury surfaces with interposed SAMs: Hg-SAM/SAM-Hg as mentioned in this paper.
Abstract: Alkanethiol self-assembled monolayers (SAMs) on a mercury surface are used to build a junction consisting of two opposing mercury surfaces with interposed SAMs: Hg-SAM/SAM-Hg. The liquid mercury surface provides a support for the SAM that is smooth, compliant, free of defects, and without the incommensurate lattice properties that characterize solid metal surfaces. The thickness of the dielectric (∼30–90 A) in this junction can be easily changed by using alkanethiols with different lengths. From capacitance measurements, a dielectric constant of 2.7±0.3 is calculated for the SAMs. The conductivity of SAMs on the Hg surface is σ=6±2×10−15 Ω−1 cm−1, a value close to that of bulk polyethylene. The junction sustains an electric field of 6 MV/cm.
17 Aug 1998
TL;DR: In this article, the authors investigated the degradation of the breakdown electric field resulting from surface roughness, the effect of gas pressure and the performance of the insulator structure under bipolar stress.
Abstract: The authors investigate a novel insulator concept which involves the use of alternating layers of conductors and insulators with periods less than 1 mm. These structures perform many times better (about 1.5 to 4 times higher breakdown electric field) than conventional insulators in long pulse, short pulse and alternating polarity applications. They present their ongoing studies investigating the degradation of the breakdown electric field resulting from surface roughness, the effect of gas pressure and the performance of the insulator structure under bipolar stress. Further, they present their initial modeling studies.
TL;DR: In this article, the authors demonstrate that parallel electric fields may be a fundamental particle acceleration mechanism in astrophysical plasmas by comparing the inferred parallel potentials of electrostatic shocks with particle energies.
Abstract: Electric field and energetic particle observations by the Fast Auroral Snapshot (FAST) satellite provide convincing evidence of particle acceleration by quasi-static, magnetic-field-aligned (parallel) electric fields in both the upward and downward current regions of the auroral zone. We demonstrate this by comparing the inferred parallel potentials of electrostatic shocks with particle energies. We also report nonlinear electric field structures which may play a role in supporting parallel electric fields. These structures include large-amplitude ion cyclotron waves in the upward current region, and intense, spiky electric fields in the downward current region. The observed structures had substantial parallel components and correlative electron flux modulations. Observations of parallel electric fields in two distinct plasmas suggest that parallel electric fields may be a fundamental particle acceleration mechanism in astrophysical plasmas.
TL;DR: The FAST satellite mission as discussed by the authors investigates plasma processes occurring in the low altitude auroral acceleration region, where magnetic field-aligned currents couple global magnetospheric current systems to the high latitude ionosphere.
Abstract: The FAST satellite mission investigates plasma processes occurring in the low altitude auroral acceleration region, where magnetic field-aligned currents couple global magnetospheric current systems to the high latitude ionosphere. In the transition region between the hot tenuous magnetospheric plasma and the cold, dense ionosphere, these currents give rise to parallel electric fields, particle beams, plasma heating, and a host of wave-particle interactions. FAST instruments provide observations of plasma particles and fields in this region, with excellent temporal and spatial resolution combined with high quantitative accuracy. The spacecraft data system performs on-board evaluation of the measurements to select data “snapshots” that are stored for later transmission to the ground. New measurements from FAST show that upward and downward current regions in the auroral zone have complementary field and particle features defined by upward and downward directed parallel electric field structures and corresponding electron and ion beams. Direct measurements of wave particle interactions have led to several discoveries, including Debye-scale electric solitary waves associated with the acceleration of upgoing electron beams and ion heating, and the identification of electrons modulated by ion cyclotron waves as the source of flickering aurora. Detailed quantitative measurements of plasma density, plasma waves, and electron distributions associated with auroral kilometric radiation source regions yield a consistent explanation for AKR wave generation.
Patent•
15 Jan 1998
TL;DR: An Electromagnetic Shield for Smartcards as discussed by the authors provides shielding of contactless smartcards or RFID tags from electromagnetic radiation which imparts energy to power the contacts and thus prevents surreptitious, wireless exchanges of digital data with a remote transceiver.
Abstract: An Electromagnetic Shield for Smartcards provides shielding of contactless smartcards or RFID tags from electromagnetic radiation which imparts energy to power the contactless smartcards or RFID tags and thus preventing surreptitious, wireless exchanges of digital data with a remote transceiver. The electromagnetic shield is made of a soft magnetic alloy with a very high initial and maximum magnetic permeability, which has been fully hydrogen annealed to develop optimum magnetic shielding properties. In the preferred embodiment, this magnetic shielding material is sandwiched between two plastic reinforcing shells which allow very thin shielding materials to be used with little regard for their resistance to permanent deformation. The relatively high intrinsic electrical conductivity of the magnetic shielding material sufficiently simulates a Faraday cage to further shield a contactless smartcard/RFID tag from electric fields as well. Four embodiments for contactless smartcards as well as one for a military identification tag and one for a pill shaped RFID tag are presented.
TL;DR: In this article, an augmented constitutive model that accounts for the temperature-dependent piezoelectric properties was proposed to extrapolate nonlinear effects measured at one temperature to other temperatures with good accuracy.
Abstract: This paper presents research results on the electro–thermomechanical behavior of piezoelectric ceramics for use in actuator applications with an emphasis on ferroelectric fatigue. The material being investigated is a lead zirconate titanate piezoelectric ceramic with the composition PbZr0.53Ti0.47O3 (PZT-5H). Results presented in this paper include an augmented constitutive model that accounts for the temperature-dependent piezoelectric properties. Using this model, nonlinear effects measured at one temperature can be extrapolated to other temperatures with good accuracy. Experimental studies into 180° and 90° polarization switching of PZT-5H indicate that the dielectric flux to dipole the material appears to be an adequate criterion for predicting this nonlinear switching behavior. Fatigue studies show that material degradation is strongly influenced by temperature and by the magnitude of the applied electric field. Above a critical temperature, PZT-5H no longer fatigues in the presence of large electric...
TL;DR: In this paper, a modification of dipole emission that is due to its optical environment is calculated for planar layered structures, and the dipole is included by using additive source terms for the electric field that depend on dipole orientation and wave polarization.
Abstract: Modification of dipole emission that is due to its optical environment is calculated for planar layered structures. The layers are optically described by standard matrix techniques, and the dipole is included by using additive source terms for the electric field that depend on dipole orientation and wave polarization. These source terms also allow coupling through evanescent waves. We emphasize the applicability of this method to cases in which the power distribution into various modes is affected: dipole emission into guided modes and emission distribution into the various modes of structures that contain multilayer reflectors, such as microcavities.
TL;DR: In this article, a new type of spatially coherent plasma structure that is associated with quasistatic, magnetic-field-aligned electric fields in space plasmas is reported.
Abstract: We report a new type of spatially coherent plasma structure that is associated with quasistatic, magnetic-field-aligned electric fields in space plasmas. The solitary structures form in a magnetized plasma, are multidimensional, and are highly supersonic. The size along ${\mathbf{B}}_{0}$ is a few ${\ensuremath{\lambda}}_{D}$ and increases with increasing amplitude, unlike a classical soliton. The perpendicular size appears to be influenced by ion motion. We show that the structures facilitate ion-electron momentum exchange and suggest that an aggregate of structures may play a role supporting large-scale, parallel electric fields.
TL;DR: In this article, it was shown that the sub-Alfvenic, low-beta interaction can be described by an anisotropic conducting atmosphere joined to an Alfven wing as one extreme case and the Jovian ionosphere as the other extreme case.
Abstract: Recent observations by the Galileo spacecraft and Earth-based techniques have motivated us to reconsider the sub-Alfvenic interaction between the Galilean satellites of Jupiter and the magnetosphere. (1) We show that the atomic processes causing the interaction between the magnetoplasma and a neutral atmosphere can be described by generalized collision frequencies with contributions from elastic collisions, ion pickup, etc. Thus there is no fundamental difference in the effect of these processes on the plasma dynamics claimed in the recent literature. For a magnetic field configuration including possible internal fields, we show that the sub-Alfvenic, low-beta interaction can be described by an anisotropically conducting atmosphere joined to an Alfven wing as one extreme case and the Jovian ionosphere as the other extreme case. (2) The addition of a small magnetic field of internal origin does not modify the general Alfven wing model qualitatively but only quantitatively. All magnetic moments discussed in the literature for In are small in this sense. For an aligned internal dipole and ambient Jovian magnetic field the interaction will be enhanced by focusing of the electric field. (3) A qualitative change occurs by the additional occurrence of closed magnetic field lines for larger internal magnetic fields as in the case of Ganymede. Here the focusing is even enhanced. (4) The first discussion of nonstationary plasma flows at the satellites shows that electromagnetically induced magnetic fields may play an important role if the satellite interiors are highly conducting. From the point of view of the external excitation, induction effects may be strong for Callisto, In, Europa, and Ganymede in order of decreasing importance. The magnetic field observations at the first Callisto encounter can be explained by these effects.
TL;DR: In this paper, the authors investigate self-consistent particle acceleration near a pulsar polar cap by the electrostatic field due to the effect of inertial frame dragging and find that stable acceleration zones may occur at some distance above the surface, where curvature radiation dominates the electron and positron energy losses.
Abstract: We investigate self-consistent particle acceleration near a pulsar polar cap (PC) by the electrostatic field due to the effect of inertial frame dragging. Test particles gain energy from the electric field parallel to the open magnetic field lines and lose energy by both curvature radiation (CR) and resonant and nonresonant inverse Compton scattering (ICS) with soft thermal X-rays from the neutron star (NS) surface. Gamma rays radiated by electrons accelerated from the stellar surface produce pairs in the strong magnetic field, which screen the electric field beyond a pair formation front (PFF). Some of the created positrons can be accelerated back toward the surface and produce γ-rays and pairs that create another PFF above the surface. We find that ICS photons control PFF formation near the surface, but because of the different angles at which the electron and positron scatter the soft photons, positron-initiated cascades develop above the surface and may screen the accelerating electric field. Stable acceleration from the NS surface is therefore not possible in the presence of dominant ICS energy losses. However, we find that stable acceleration zones may occur at some distance above the surface, where CR dominates the electron and positron energy losses and there is up-down symmetry between the electron and positron PFFs. We examine the dependence of CR-controlled acceleration zone voltage, width, and height above the surface on parameters of the pulsar and its soft X-ray emission. For most pulsars, we find that acceleration will start at a height of 0.5-1 stellar radii above the NS surface.
TL;DR: The optical properties of random metal-dielectric thin films (referred also to as semicontinuous metal films) are of great interest, in large part because of their high potential for various applications as discussed by the authors.
Abstract: The optical properties of random metal-dielectric thin films (referred also to as semicontinuous metal films) are of great interest, in large part because of their high potential for various applications. Two-dimensional (2d) semicontinuous metal films are usually produced by thermal evaporation or sputtering of metal onto an insulating (dielectric) substrate. In the growing process small metallic grains are formed on the substrate first. As the film grows, the metal concentration increases and coalescences occur, so that irregularly shaped clusters are formed on the substrate eventually resulting in 2d fractal structures. At the percolation threshold, the sizes of the fractal structures diverge and a continuous conducting path of metal appears between the ends of the sample. At higher surface coverage, the film is mostly metallic, with voids of irregular fractal shapes. As further coverage increases, the film becomes uniform. We calculated the field distributions on a semicontinuous film at the fundamental and generated (in nonlinear optical processes) frequencies using a very effective numerical method based on the real space renormalization group (RSRG) approach. Our RSRG calculations demonstrate the large fluctuations for the intensity of the local electric fields.
TL;DR: DNA molecules can be manipulated in aqueous solution in a manner analogous to optical trapping by mixing static and oscillating electric fields, which should be useful in microdevices for manipulation of small quantities or single molecules of DNA.
TL;DR: In this article, the Freja satellite at altitudes around 1700 km in the high-latitude magnetosphere is used to study ion energization perpendicular to the geomagnetic field.
Abstract: Observations obtained by the Freja satellite at altitudes around 1700 km in the high-latitude magnetosphere are used to study ion energization perpendicular to the geomagnetic field. Investigations ...
TL;DR: In this article, the authors show that dispersionless injections can be understood as a consequence of changes in the electric and magnetic fields by modeling an electron injection event observed early on January 10, 1997 by means of a test-particle simulation.
Abstract: The term “dispersionless injection” refers to a class of events which show simultaneous enhancement (injection) of electrons and ions with different energies usually seen at or near geosynchronous orbit. We show that dispersionless injections can be understood as a consequence of changes in the electric and magnetic fields by modeling an electron injection event observed early on January 10, 1997 by means of a test-particle simulation. The model background magnetic field is a basic dipole field made asymmetrical by a compressed dayside and a weakened nightside. The transient fields are modeled with only one component of the electric field which is westward and a consistent magnetic field. These fields are used to model the major features of a dipolarization process during a substorm onset. We follow the electrons using a relativistic guiding center code. Our simulation results, with an initial kappa electron energy flux spectrum, reproduce the observed electron injection and subsequent drift echoes and show that the energization of injected electrons is mainly due to betatron acceleration of the preexisting electron population at larger radial distances in the magnetotail by transient fields.
TL;DR: A model that quantitatively describes the performance of microfabricated electrophoretic devices filled with linear polyacrylamide as replaceable sieving material for single-stranded DNA analyses is presented and the dependence of resolution on various separation parameters such as selectivity, diffusion, injector size, device length, and channel folding was investigated.
Abstract: We present a model that quantitatively describes the performance of microfabricated electrophoretic devices filled with linear polyacrylamide as replacable sieving material for single-stranded DNA analyses. The dependence of resolution on various separation parameters such as selectivity, diffusion, injector size, device length, and channel folding was investigated. A previously predicted dependence of longitudinal diffusion coefficient on electric field strength has been verified. We have used this model to develop and optimize microfabricated electrophoretic devices for DNA analyses. For single-color DNA sequencing mixtures, we routinely achieve separations of 400 bases in under 14 min at 200 V/cm, and separation of 350 bases in only 7 min at 400 V/cm, with a minimum resolution of R = 0.5. Our results also indicate reduced fragment biasing and efficient sample stacking for DNA sample loading on microfabricated devices.
TL;DR: In this paper, the authors used ac-coupled sensors, induction coils for the magnetic field, and an electric field amplifier developed for marine controlled-source applications for seafloor magnetotelluric measurements.
Abstract: Induction in electrically conductive seawater attenuates the magnetotelluric (MT) fields and, coupled with a minimum around 1 Hz in the natural magnetic field spectrum, leads to a dramatic loss of electric and magnetic field power on the sea floor at periods shorter than 1000 s. For this reason the marine MT method traditionally has been used only at periods of 103 to 105 s to probe deep mantle structure; rarely does a sea‐floor MT response extend to a 100-s period. To be useful for mapping continental shelf structure at depths relevant to petroleum exploration, however, MT measurements need to be made at periods between 1 and 1000 s. This can be accomplished using ac-coupled sensors, induction coils for the magnetic field, and an electric field amplifier developed for marine controlled‐source applications. The electrically quiet sea floor allows the attenuated electric field to be amplified greatly before recording; in deep (1-km) water, motional noise in magnetic field sensors appears not to be a proble...
TL;DR: In this paper, it is shown that the rate at which metal-induced crystallization takes place is markedly enhanced in the presence of an electric field, and a thin-film transistor fabricated from such a film exhibits a field-effect mobility of 58 cm2.
Abstract: Thin films of polycrystalline silicon are of great importance for large-area electronic applications, providing, for example, the switching electronics in many flat-panel displays. Polycrystalline silicon is typically produced by annealing films of amorphous silicon1 that have been deposited from the vapour phase, and much research is focused on lowering the crystallization temperature. It is known that the solid-phase crystallization temperature of amorphous silicon can be reduced by the addition of certain metals2, such as nickel3. Here we show that the rate at which this metal-induced crystallization takes place is markedly enhanced in the presence of an electric field. For example, the crystallization time at 500 °C decreases from 25 hours to 10 minutes on application of a modest (80 V cm−1) electric field. No residual amorphous phase can be detected in the films. A thin-film transistor fabricated from such a film exhibits a field-effect mobility of 58 cm2 V−1 s−1, thereby demonstrating the practical utility of these materials.
TL;DR: In this paper, numerical simulations were performed to predict the performance of microwave plasma reactors with various reactor geometries, including the calculation of the electric field distribution using the finite integration theory and the determination of the plasma density distribution based on a breakdown field algorithm.
Abstract: Numerical simulations were performed to predict the performance of microwave plasma reactors with various reactor geometries. The simulations include the calculation of the electric field distribution using the finite integration theory and the determination of the plasma density distribution based on a breakdown field algorithm. One reactor geometry with a cavity having the shape of a rotational ellipsoid turned out to be very promising. The electric field within this cavity exhibits two pronounced maxima at the two focal points of the ellipsoid. By coupling microwave energy into one maximum via an antenna, large electric field strengths can be generated in the counter maximum. This effect has been used to excite intense discharges that are very stable, spatially extended, homogeneous, and free from wall contact. These discharges were employed for the chemical vapor deposition of large area diamond wafers.