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Author

Takao Kaga

Bio: Takao Kaga is an academic researcher. The author has contributed to research in topics: Glow discharge & Cubic zirconia. The author has an hindex of 5, co-authored 9 publications receiving 141 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, it has been suggested that a large amount of hydrogen which is not bonded with Si is incorporated in a-Si: H films prepared from Si2H6 and this might be reflected in the dark and photoconductivity of the films.
Abstract: Optical emission spectroscopy and mass spectrometry have been employed as diagnostic tools for studying the glow discharge plasma of pure SiH4 and pure Si2H6. It has been suggested that the dimeric species play an important role in the deposition of a-Si: H from Si2H6 glow discharge in contrast to the monomeric species of SiH dominant in the deposition from pure SiH4. A large amount of hydrogen which is not bonded with Si is incorporated in a-Si: H films prepared from Si2H6 and this might be reflected in the dark and photoconductivity of the films.

67 citations

Journal ArticleDOI
TL;DR: In this paper, the influence of power source frequency on the film properties of glow discharge (GD) amorphous silicon has been studied in the range from 10 kHz to 50 MHz, and it has been demonstrated through mass spectrometric measurements that the internal stress is caused by ion bombardment on the growing surface of the film.
Abstract: The influence of power-source frequency on the film properties of glow-discharge (GD) amorphous silicon has been studied in the range from 10 kHz to 50 MHz. Mechanical property, rather than photoelectric properties of the film, is highly influenced by the frequency, i.e., compressive internal stress is stored in the film when deposited from SiH4 plasma operated by a frequency lower than 500 kHz. It has been demonstrated through mass spectrometric measurements that the internal stress is caused by ion bombardment on the growing surface of the film.

27 citations

Patent
03 Feb 1992
TL;DR: In this article, a stable basic zirconia sol can be prepared by adding to an acidic aqueous zirconsia sol a dispersion stabilizer selected from the group consisting of a water-soluble organic acid having a hydroxyl group and a water soluble organic compound having at least two hydroxy groups.
Abstract: A stable basic zirconia sol can be prepared by adding to an acidic aqueous zirconia sol a dispersion stabilizer selected from the group consisting of a water-soluble organic acid having a hydroxyl group and a water-soluble organic compound having at least two hydroxyl groups, and thereafter adjusting the sol with a basic compound to pH 6 to 14.

18 citations

Journal ArticleDOI
TL;DR: Glow discharge deposition of a-Si:H:F from SiH3F as well as SiH2F2 gas has been studied in comparison to that from siH4 as discussed by the authors.
Abstract: Glow discharge deposition of a-Si:H:F from SiH3F as well as SiH2F2 gas has been studied in comparison to that from SiH4. Deposition rate from SiH3F exceeds that from SiH4 by 2–3 times in magnitude under a low-power deposition condition.

14 citations

Patent
25 Sep 1987
TL;DR: In this paper, a ZrO 2 sol containing dispersed metal hydroxide stabilizer is subjected to dehydration, drying and calcination by conventional method, and the obtained Zr O 2 fine powder containing the stabilizer can be converted to a sintered material by conventional sintering process.
Abstract: PURPOSE: To obtain fine powder of ZrO 2 having high density and strength and useful as a raw material for excellent zirconia ceramics, by adding hydroxide of one or more metals selected from Ca, Mg, Y and lanthanide elements as a stabilizer to a zirconia sol and subjecting the mixture to dehydration, drying and calcination. CONSTITUTION: A ZrO 2 sol containing ZrO 2 having particle diameter of preferably 500W5,000Å is added with hydroxide of one or more metals selected from Ca, Mg, Y and lanthanide elements such as Ce. The amount of the hydroxide is especially preferably 0.1W10mol.% in stabilized ZrO 2 in terms of oxide. The obtained ZrO 2 sol containing dispersed metal hydroxide stabilizer is subjected to dehydration, drying and calcination by conventional method. The calcination is carried out at 700W1,200°C and the obtained ZrO 2 fine powder containing the stabilizer can be converted to a sintered material by conventional sintering process. COPYRIGHT: (C)1988,JPO&Japio

6 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the formation kinetics of μc-Si:H has been investigated through the film depositions and plasma diagnoses in widely-scanned glow discharge plasma conditions; RF power density, SiH 4 /H 2 ratio and substrate temperature.
Abstract: The formation kinetics of μc-Si:H has been investigated through the film depositions and plasma diagnoses in widely-scanned glow discharge plasma conditions; RF power density, SiH 4 /H 2 ratio and substrate temperature. The roles of H and SiH x adsorbed on the surface as well as impinging ions have been discussed in relation to volume fraction and crystallite size of μc films, and continuous control of crystallite size has been demonstrated using a triode system. Hall mobility of the deposited μc-Si:H films has also been presented as a function of the volume fraction of μc.

531 citations

Journal ArticleDOI
TL;DR: In this article, a radiofrequency plasma-enhanced chemical vapor deposition method was used for the deposition of hydrogenated microcrystalline silicon (µc-Si:H) at a relatively high working pressure.
Abstract: The deposition of hydrogenated microcrystalline silicon (µc-Si:H) at a relatively high working pressure is performed using a conventional radio-frequency plasma-enhanced chemical vapor deposition method. Correlation of the deposition rate and crystallinity with deposition parameters, such as working pressure, flow rate, dilution ratio and input RF power, are studied. It was found that the deposition rate exhibits a maximum at around 4 Torr and that the crystallinity of films decreases monotonically with increasing pressure. The combination of SiH4 depletion and high working pressure in the plasma is necessary to improve the crystallinity of films deposited at a high rate. Consequently, a high deposition rate of 9.3 A/s is achieved with high crystallinity and low defect density.

207 citations

Journal ArticleDOI
TL;DR: In this article, the effect of plasma excitation frequency on the deposition rate and on the optical and electrical properties of amorphous silicon film was studied over the range 25-150 MHz.
Abstract: The effect of plasma excitation frequency on the deposition rate and on the optical and electrical properties of amorphous silicon film is studied over the range 25–150 MHz. Deposition rates as high as 21 A/sec are obtained at ∼70 MHz, which is a factor of 5–8 larger than typical rates obtained for the conventional 13.56-MHz silane glow-discharge system. Only minor changes occur in the defect density (as measured by the photothermal deflection spectroscopy method), the optical bandgap, and the electrical conductivity over this frequency range. In a preliminaryinterpretation given here, the large variation of the deposition rate as a function of excitation frequency is explained in terms of changes in the electron energy distribution function.

181 citations

Journal ArticleDOI
TL;DR: In this article, the energy and angular distribution of ions striking the electrodes in low-pressure capacitively coupled rf discharges are studied using a Monte Carlo model for ion trajectories and a parametric model for the time-dependent electric field within the sheath.
Abstract: The energy and angular distribution of ions striking the electrodes in rf discharges are of interest with respect to the application of such discharges to the processing of semiconductor materials. The ability to fabricate small (< 1 μm) semiconductor features using the plasma etching process results, in part, from the energetic and anisotropic flux of ions which strike the semiconductor surface. In this paper the energy and angular distribution of ions striking the electrodes in low‐pressure capacitively coupled rf discharges are studied using a Monte Carlo model for ion trajectories and a parametric model for the time‐dependent electric field within the sheath. Energy and angular distributions are discussed as a function of rf frequency, ion mass, and the mean‐free path between charge exchange collisions within the sheath. The ion energy distribution is found to be characterized by a scaling parameter proportional to (rf frequency × sheath thickness)2 × ion mass/(sheath voltage); small values of this parameter yield bimodal distributions, intermediate values yield distributions peaked at the maximum sheath potential, and high values yield distributions peaked at the average sheath potential. The ion energy distribution is also examined for different values of the dc and rf components of the sheath potential and for different models for the electric field within the sheaths. When the dc component of the sheath potential is small compared to the rf amplitude, a large thermal component to the ion energy distribution results. The implication of this result and that for the angular distribution of ions incident on the electrodes is discussed with respect to the isotropy of the etch obtained during plasma etching of semiconductor materials.

168 citations

Journal ArticleDOI
TL;DR: In this article, the deposition kinetics of hydrogenated amorphous silicon from a SiH4 glow discharge plasma have been investigated by examining the diffusion of SiH3 monoradicals in the discharge free space within a triode reactor.
Abstract: The deposition kinetics of hydrogenated amorphous silicon (a‐Si:H) from a SiH4 glow‐discharge plasma have been investigated by examining the diffusion of SiH3 monoradicals in the discharge‐free space within a triode reactor. This experiment suggests that the SiH3 radicals are responsible for about 37% of the total deposition rate of a‐Si:H in a conventional SiH4 glow‐discharge process. The contribution of other radicals and atoms to the deposition rate is also discussed through the analysis of reaction‐rate constants.

125 citations