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  • 1
    Electronic Resource
    Electronic Resource
    Step responses of radio-frequency capacitively coupled discharges (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 2093-2105 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Models capturing the periodic steady-state behavior of rf capacitively coupled discharges are now commonplace. New plasma sources have been motivated by selectivity, charge-damage mitigation, and general process control needs in plasma processing of electronic materials. These new sources require models that can accurately capture the transient behavior of the plasma source. Such models are not commonplace because the behavior of transport parameters in transients is still not well understood and because the problem is inherently stiff, i.e., widely disparate time scales are important. In this paper, we present the results of an investigation of the simplest type of transient, known as a step disturbance, in a 2 cm gap parallel-plate argon discharge at 1 Torr. As examples, two classes of step transients are considered: step increases in the peak-to-peak (pp) applied voltage (300 to up to 450 V pp) and step decreases (300 to as low as 150 V pp). The resulting transients are interpreted in terms of time scales representative of electron and ion motion in the sheath, ionization dynamics, and neutral transport processes. The possibility of using these transients as a means of process identification is discussed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366019
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  • 2
    Electronic Resource
    Electronic Resource
    Contrast mechanisms in scanning ion microscope imaging for metals (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 611-613 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The contrast of the secondary electron images in scanning ion microscopy (SIM) is compared with that in scanning electron microscopy (SEM) with ultrahigh vacuum for Al, Cu, Ag, and Au metals deposited on the Si(100) clean surface. The order of the secondary electron yields as a function of the atomic number (Z2) for ion bombardment is opposite to that for electron bombardment. The brightness of the secondary electron images observed by a focused Ga+ ion beam at 30 keV decreases with increasing Z2, while that by the electron beam increases with Z2. On the other hand, the order of the total secondary ion yields in SIM increases with Z2. The secondary electron image observed by a focused Ar+-ion beam at 3 keV shows the similar contrast to that of the Ga+-ion beam. The different Z2 dependence of the secondary electron yields between SEM and SIM was quantitatively confirmed by the total secondary electron spectra and is discussed based on the range profile below the surface, and it is concluded that the decrease of the secondary electron yields in SIM is attributed to the increase of the reflected ions at the surface with increasing Z2. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121872
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  • 3
    Electronic Resource
    Electronic Resource
    Simulations of step responses of electronegative radio-frequency capacitively coupled discharges (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 1848-1858 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The transient response of electronegative radio-frequency glow discharges is important for process control, charge free etching, and highly selective etch applications. The step response of typical electronegative process gases (silane at 1 Torr and chlorine at 100 mTorr) is studied using a drift-diffusion model for silane and a three-moment model for chlorine. The silane simulations include a blocking capacitor whereas the chlorine results do not. For the silane results with a blocking capacitor in series with the plasma, it is found that there are three types of transients. Depending on the final steady-state value of the source rf voltage, the step response can be characterized either by smooth transitions in the number densities of species in the discharge from one steady state to the next, temporary extinction of the discharge or a discharge mode characterized by temporary extinction and reignition of the discharge. In the case of silane definite thresholds separate the phenomena. The step response of the chlorine discharges is always characterized by a smooth transition from one steady state to the next. Smooth transitions from one steady state to the next in the case of step decreases in the source voltage are possible since decrease of the negative ion density in the bulk is controlled by ion–ion recombination. It appears that the temporary extinction of the discharge and natural pulsed steady state is the consequence of how the voltage is divided between the gap and the blocking capacitor during the transient and the fact that the attachment coefficient becomes larger than the ionization coefficient at low values of reduced electric field. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368343
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  • 4
    Electronic Resource
    Electronic Resource
    A two-dimensional model of laser ablation of frozen Cl2: A possible neutral beam source for etching applications (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 1146-1155 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Charge damage considerations are prompting the development of neutral beam sources for etching applications. Anisotropic etching with hyperthermal Cl2 and SF6 beams has been demonstrated. We describe a two-dimensional plasma chemistry fluid model of laser ablation of frozen Cl2 in vacuum as a neutral beam source. In this scheme an externally applied electric field would be used to enhance the dissociation rate of Cl2 potentially providing an enhanced Cl content in the beam for a greater etch rate. Laser ablation generated neutral beams also may contain a desirable and controllable ion content which may be used to further enhance the etch rate. Limitations of the concept are discussed. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362852
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  • 5
    Electronic Resource
    Electronic Resource
    Humidity sensor using sintered zircon with alkali-phosphate (1985)
    Springer
    Journal of materials science 20 (1985), S. 3027-3033 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A ceramic humidity sensor using alkali phosphate (tribasic), phosphoric acid and zircon as raw materials was studied. The ceramic body prepared by doping with sodium phosphate consists of zircon, Nasicon and probably glassy sodium polyphosphate. The sensitivity for humidity can be improved by doping with sodium phosphate and phosphoric acid. The specimen in which the mole ratio (Na/P) is nearly equal to one is desirable for a humidity sensor with respect to sensitivity, and the impedance is 2×106 Ωcm or below in a dry atmosphere. The formation of Nasicon explains the decrease of impedance in the low humidity region and a decrease of impedance in the high humidity region can be achieved by the formation of sodium polyphosphate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00553069
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of sorbed water on the electrical resistance of polysodium phosphate thin films (1986)
    Springer
    Journal of materials science 21 (1986), S. 3751-3758 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Measurements have been made of complex impedance and sorbed water of polysodium phosphate. The resistance and its activation energy decreases with an increase in the amount of sorbed water. The amount of sorbed water is strongly affected by the Na2O/P2O5 mol ratio. The humidity dependence of the activation energy and the resistance is lowered by decreasing the average chain length of polysodium phosphate. This results in an increase in the amount of sorbed water. Especially, in low humidity conditions, the decrease in the resistance and the activation energy are achieved by increasing the concentration of the strongly acidic PO-H group. These improvements can not be achieved by increasing the Na2O/P2O5 mol ratio. In a humid atmosphere, the resistance of the film, in which the Na2O/P2O5 mol ratio is less than 0.8, is inversely proportional to the concentration of the strongly acidic PO-H group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02431609
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  • 7
    Electronic Resource
    Electronic Resource
    Theoretical study of the deformation densities of d electrons in K2[PdCl6] and K2[PtCl6] crystals (1996)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 251-259 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Aspherical distributions of the d electrons in dipotassium palladium hexachloride, K2[PdCl6], and dipotassium platinum hexachloride, K2[PtCl6], crystals were analyzed by theoretical calculations. Hartree–Fock and configuration interaction calculations were performed for [PdCl6]2− and [PtCl6]2− with and without taking into account the Madelung potentials, using a model potential method. The major relativistic effects were incorporated in the model potentials for Pd and Pt. The deformation-density maps calculated were similar to those given by the X-ray diffraction method. The theoretical result suggested that the positive peaks on the threefold axes and the negative peaks on the metal—Cl bond axis correspond to the excess d electrons (4d of Pd and 5d of Pt) in the t2g (dxy, dxz, dyz) orbitals and the electron deficiency in the eg (dz2,dx2−y2) orbitals, respectively. The positive and negative peak heights were calculated to be +1.8 and −0.8 e Å−3 for [PdCl6]2− and +1.2 and −0.6 e Å−3 for [PtCl6]2−. The effective charges and effective radii of Pd and Pt, and the number of electrons in the t2g, eg and t1u orbitals, were calculated by direct integration. The effects of the Madelung potential and electron correlation on the charge distributions of [PdCl6]2− and [PtCl6]2− were also analyzed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S010876819501202X
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  • 8
    Electronic Resource
    Electronic Resource
    [(R)-1,2-Bis(allyloxycarbonyl)ethyl]bis(dimethylglyoximato-N,N')[(R)-1-phenylethylamine]cobalt(III) (1996)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 1086-1089 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270195014399
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  • 9
    Electronic Resource
    Electronic Resource
    Humidity sensor composed of a microporous film of polyethylene-graft-poly-(2-acrylamido-2-methylpropane sulfonate) (1987)
    Springer
    Polymer bulletin 18 (1987), S. 501-506 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Inside a microporous polyethylene film, 2-acrylamido-2-methylpropane sulfonic acid was graft polymerized by ultraviolet irradiation. A humidity sensor was fabricated by depositing gold electrodes on both sides of the grafted film. The impedance was measured as a function of humidity for the acid and alkali salts of sulfonate. The sensor has long term stability and is resistant to water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00255333
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  • 10
    Electronic Resource
    Electronic Resource
    Mössbauer spectroscopic study of phthalocyanineiron/II/ in NaY zeolite (1989)
    Springer
    Journal of radioanalytical and nuclear chemistry 137 (1989), S. 287-297 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Phthalocyanineiron/II/ in NaY zeolite was synthesized via various processes from an iron carbonyl compound into NaY zeolite in gaseous phase. Mössbauer spectra of the final product /phthalocyanineiron/II// and the precursor species /iron oxide and [phthalocyaninato/2-/]bis/pyridine/iron/II// in NaY zeolite were measured to characterize the chemical and physical states of the iron species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02163554
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