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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Vacuum Society
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Journal DOI :
The Korean Vacuum Society
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Volume & Issues
Volume 8, Issue 4B - Dec 1999
Volume 8, Issue 4A - Nov 1999
Volume 8, Issue 3B - Aug 1999
Volume 8, Issue 3A - Aug 1999
Volume 8, Issue 2 - Mar 1999
Volume 8, Issue 1 - Feb 1999
Selecting the target year
A Study of the numerical method on the molecular transition flow for the rotating blades
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 83~92
Pumping performance of a disk-type molecular drag pump for a hybrid molecular pump is numerically analyzed by the direct simulation onte-Carlo method. The flows in pumping channels are three-dimensional (3D) in a molecular transition regime. The main difficulty in modeling a 3D case comes from the rotating frame of reference. Thus, trajectories of particles ar no longer straight lines. In the present study, trajectories of particles are calculated by integrating a system of differential equations including the Coriolis and centrifugal forces. The null-collisions. The present numerical results molecular model is used for calculation of molecular collisions. The present numerical results significantly disagree with the previously known ones. This indicates that an actual pumping passage is very limited to a narrow region due to the significant backstreaming of molecules from the outlet.
A Study on the thermal and electrical stability of PVDF organic thin films fabricated by physical vapor deposition method.
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 93~101
The purposed of this paper is to investigate the electrical and thermal stability of Polyvinylidene fluoride(PVDF) organic thin films prepared by the vapor deposition method. The differential scanning calorimetry curve of the PVDF organic thin films prepared by increasing substrate temperature showed that the melting curve increased from
. This result implied that the PVDF organic thin film prepared by increasing substrate temperature increased intermolecular force in the crystalline region. The anomalous properties in dielectric constant and dielectric loss at low frequency and high temperature were described for PVDF organic thin film containing impurity carriers. It was confirmed that in view of electric conductive characteristics the ohm's law is satisfied in the range of lower electric field and ln J was proportional to the electric field ln E as like the conventional property of ionic conduction in the range of higher electric field. It was confirmed that major carrier of conductivity was ions. The electrical stability was improved according to an increase of the substrate temperature. On the basis of this experimental result, it could be observed that the optimum temperature of substrate for the electrical and thermal stability was at
Exposure Time and X-Ray Absorber thickness in the LIGA Process
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 102~110
The LIGA X-ray exposure step was modelled into three inequalities, by assuming that the X-ray energy attenuated within a resist is deposited only in the localized range of the resist. From these inequalities, equations for the minimum and maximum exposure times required for a good quality microstructure were obtained. Also, an equation for the thickness of an X-ray mask absorber was obtained from the exposure requirement of threshold dose deposition. The calculation method of the synchrotron radiation power from a synchrotron radiation source was introduced and applied to an X-ray exposure step. A power from a synchrotron radiation source was introduced and applied to an X-ray exposure step/ A power function of photon energy, approximating the attenuation length of the representative LIGA resist, PMMA, and the mean photon energy of the XZ-rays incident upon an X-ray mask absorber were applied to the above mentioned equations. Consequently, the tendencies of the minimum and maximum exposure and with respect to mean photon energy and thick ness of PMMA was obtained. Additionally, the tendencies of the necessary thickness of PMMA and photon energy of the X-ray mask absorber with respect to thickness of PMMA and photon energy of the X-rays incident upon an X-ray mask absorber were examined. The minimum exposure time increases monotonically with increasing mean photon energy for the same total power density and is not a function of the thickness of resist. The minimum exposure time increases with increasing mean photon energy for the same total power density in the case of the general LIGA process, where the thickness of PMMA is thinner than the attenuation length of PMMA. Additionally, the minimum exposure time increases monotonically with increasing thickness of PMMA. The maximally exposable thickness of resist is proportional to the attenuation length of the resist at the mean photon energy with its proportional constant of ln
. The necessary thickness of a gold X-ray mask absorber due to absorption edges of gold, increases smoothly with increasing PMMA thickness ratio, and is independent of the total power density itself. The simplicity of the derived equations has made clearly understandable the X-ray exposure phenomenon and the correlation among the exposure times, the attenuation coefficient and the thickness of an X-ray mask absorber, the attenuation coefficient and the thickness of the resist, and the synchrotron radiation power density.
In-situ structural analysis during heating of an epitaxial
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 111~115
The structural characteristics of an epitaxial
film on MgO(001) grown by sputtering were studied as a function of temperature using in-situ, real time synchrotron x-ray scattering experiments. We found that the as-grown film was single c-domain but strained at room temperature and tetragonally distorted with the c-axis normal to the film surface. Interestingly, its lattice parameters were found to be expanded in both the in-plane and the out-of -plane directions, i.e. biaxially, comparing with those of a bulk
. More importantly, as it was heated up to
, the tetragonal structure was kept up through without and any phase transition, which is usually observed in other epitaxial ferroelectric thin films.
Fabrication and characterization of fe-Ni Invar alloy thin films
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 116~120
Fe-Ni alloy thin films with about 3.5
thickness were successfully grown on Al-killed steel substrates employing DC magnetron sputtering method, and then the4 film properties were characterized. The deposited film exhibited a fibre texture structure with the relationship of
. We found that the adhesion between the film and the substrate was fairly good considering no debonding behavior after the thermal cyclic test of 5,000 times from room temperature to
. Also we found that the Fe-Ni alloy deposition induced a significant decrease of thermal expansion in the film processing, a new material system with much lower thermal expansion coefficient which can be applied more as shadow mask materials than an Al-killed steel sheet.
Design of Self-ion assisted beam source (SIAB) based on electron focusing with concentric symmetrical electric field and Cu thin film growth by SIAB
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 121~126
Cu thin film was deposited by a self-ion assisted beam source (SIAB) and the assessment of the Cu films was given. Some characteristics of the source and the experimental procedure are described at various conditions such as total power, ionization efficiency, and ion current vs. deposition rate. The dependence of crystalline structure, impurity concentration, and resistivity of the Cu films deposited by SIAB on acceleration voltage are discussed.
The electrochromic properties of nickel oxide films
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 127~135
Nickel oxide films were prepard by using the electron beam evaporation technique. Coloring and bleaching experiments for cyclic durability were repeated in KOH electrolyte by cyclic voltammetry. Visible spectrophtometry was used to assess the stability of the transmittance in the degraded films. X-ray photoelectron spectroscopy results showed that the grain surface are oxygen-rich compared to the grain interiors in a NiO film. Open circuit memory of colored films is about 400hours in lN KOH. The rate of self discharge was evaluated by measuring the transmittance at 550nm of a fully oxidized NiO film. The rate of self discharge was increased polynomially with time and the film is nearly bleached after about 400hours. It was also found that the degraded film by repeated cycles in the KOH solution changed the grain shape of film surface The film prepared under a vacuum pressure of
mbar was found to be rather stable when subjected to the repeated coloring and bleaching cycles in KOH electrolyte. Band theory applied to explain the electrochromic mechanism was discussed.
The stability of
thin film prepared by thermal oxidation method
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 136~140
The stability and response time of
thin films for EC device are critical problems being solved. Those are affected by the species of electrolyte, preparation conditions and fabricating methods of specimen. In this paper, we compared the stabilities of three kinds of tungsten oxide film in electrolyte. Each of three films was prepared by different manufacturing conditions, that is, one is a thermal oxidation film of tungsten metal deposited on pure glass substrate, another is a
film made on ITO glass directly, the other is a thermally oxidized film on tungsten plate. It was observed that thermally oxidized
films has a remarkable stability (the lifetime was above
cycle). From these results, we found that the stability was closely related to the stoichiometric bonding between tungsten and oxygen atoms in addition to crystallinity and density of film.
The Structure and Electrochromic Characteristics of
thin Film with deposition Conditions and Post-Annealing
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 141~147
The electrochromic characteristics of tungsten oxide films are largely affected by deposition conditions, such as substrate temperature and gas flow rate and also post-annealing. We have considered gas flow rate and temperature as important factors having an effect on an electrical, optical phenomenon and structural variation of
. The tungsten oxide films were deposited onto ITO(20
) using rf magnetron sputtering method. In particular, the films deposited at room temperature were annealed at various temperatures in air. All specimens had crystal structure except one being deposited at room temperature with nearly amorphous-like structure. The specimen deposited at
had a structure in which the increase in deposition temperature. The specimen deposited at
had a structure in which the cations
are easily movable because of void boundaries induced by regularly arrayed large grains. The specimen deposited at
had a dense structure with small grains but it exhibited the large mobility and charge density in
because of distinct grain boundaries.
Electron mobility and low temperature magnetoresistance effect in
quantum well devices
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 148~152
the low temperature magnetoresistance effect, electron mobilities, and 2 Dimensional electron Gases (2DEG) properties were investigated in
quantum well devices. N-type
structures were fabricated by utilizing a gas source Molecular Beam Epitaxy (GSMBE). Thermal oxidation was carried out in a dry O atmosphere at
for 7 hours. Electron mobilities were measured by using a Hall effect and a magnetoresistant effect at low temperatures down to 0.4K. Pronounced Shubnikov-de Haas (SdH) oscillations were observed at a low temperature showing two dimensional electron gases (2DEG) in s tensile strained Si quantum well. The electron sheet density (ns) of
and corresponding electron mobility of 14200
were obtained at a low temperature of 0.4K from
structures with thermally grown oxides.
Characteristic absorbance of AlGaN epilayers grown on sapphire substrate
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 153~157
The dependence of the absorption edge of wurtzite
on alN mole fraction has been studied. The AlN mole fraction was varied from 0 to 1. The absorption coefficients at room temperature were determined by transmission and photothermal deflection spectroscopy. Photothermal deflection spectroscopy can be applied to determine the low absorbance values. From the results, the effective bandgaps of
alloys were determined by choosing corresponding photon energies of the positions of the absorption coefficient of
at the absorption curves of the
alloys. From the energy position of the absorption coefficient versus AlN mole fraction, a bowing parameter of 1.3eV was determined. The bowing parameter agreed quite well with the measured effective bandgaps of AlGaN alloys.
Modification and adhesion improvement of BN interfacial layers by Post-N+ implantation
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 157~164
The post ion implantation has been applied to modify early-grown BN layer and improve the adhesion of the BN films. The effect of ion implantation doses on microstructure and interlayer was investigated by FTIR and HRTEM. And the hardness and delamination life time of N+-implanted BN films were measured. With increasing the ion dose up to
,the change of IR spectrum is observed. At
, a drastic transition of cubic phase into hexagonal phase is detected. The change of microstructure of early-grown layers by ion implantation is confirmed using HRTEM. Both microhardness and delamination life time of BN films increase with ion dose. The modification model of early-grown BN layers is briefly discussed based on the displacement per atom and excess boron in the BN film induced by ion irradiation.
Modification and adhesion improvement of BN interfacial layers by Post-
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 158~158
The post ion implantation has been applied to modify early-grown BN layer and improve the adhesion of the BN films. The effect of ion implantation doses on microstructure and interlayer was investigated by FTIR and HRTEM. And the hardness and delamination life time of N+-implanted BN films were measured. With increasing the ion dose up to 5.0×1015atoms/㎠, the change of IR spectrum is observed. At 5.0×1016atoms/㎠, a drastic transition of cubic phase into hexagonal phase is detected. The change of microstructure of early-grown layers by ion implantation is confirmed using HRTEM. Both microhardness and delamination life time of BN films increase with ion dose. The modification model of early-grown BN layers is briefly discussed based on the displacement per atom and excess boron in the BN film induced by ion irradiation.
Effects of oxygen, hydrogen and nitrogen addition in the synthesis of diamond-like carbon films
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 165~171
Diamond-like carbon(DLC) films were synthesized using the rf-plasma CVD technique with the addition of small amounts of nitrogen and oxygen to a gas mixture of
. The gas flow ratio of
was 2.4:1, and 3% , 13.6% of nitrogen were added to the gas mixture of
for the deposition of DLC films. The film stress tended to decrease as the nitrogen concentration increased from 3% to 13.6%, probably due to the decrease of the number of the interlink between carbon atoms. The residual stress tended to slightly decrease when 3% of oxygen was added. Scratch tests were performed to investigate the adhesion between the DLC films and the Ti intelayer after pretreating the TiN surface with direct hydrogen plasma. The adhesion was enhanced by adding nitrogen and oxygen to the
gas mixture. The adhesion for the 3% nitrogen addition was better than that for the 13.6% nitrogen addition. The Vicker's hardness of the DLC films was measured to be 1100Hv.
Effects of axial external magnetic fields on plasma density on substrate in helical resonator plasma source
Journal of the Korean Vacuum Society, volume 8, issue 2, 1999, Pages 172~179
The axial distributions of plasma density in a helical resonator plasma with the external magnetic field have been measured using Langmuir probes. Net RF power is set to 200W and chamber pressure is varied from 0.4 mTorr to 100mTorr there are three kinds of eternal magnetic field structure applied on the helical resonator plasma. One is a uniform magnetic field, the second is a positive gradient magnetic field and the third is a negative gradient magnetic field. In the three magnetic field structures, the negative gradient magnetic field is found to show the highest increase in plasma density on the substrate compared with other magnetic structures. Plasma density profile in helical resonator is well consistent with electromagnetic field pattern obtained by computer simulation. It is also found that axial magnetic fields do not affect plasma density distribution in the plasma reactor region, but induce the increase of plasma density in the process chamber region. In order to avoid the nonuniformity of radial density profile, weak magnetic fields under 100G are applied.