• The Korean Journal of Ceramics
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• v.5 no.3
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• pp.211-216
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• 1999

Four different $\beta-Si_3N_4$ ceramics with silicon oxynitrides $[Y_10(SiO_4)_6N_2, Yb_4Si_2N_2O_7, Er_2Si_3N_4O_3, \;and La_{10}(SiO_4)_6N_2$, respectivley] as secondary phases have been fabricated by hot-pressing the $Si_3N_4-Re_4Si_2N_2O_7$ (Re=Y, Yb, Er, and La) compositions at $1820^{\circ}C$ for 2h under a pressure of 25 MPa. The high temperature strength and oxidation behavior of the hot-pressed ceramics were characterized and compared with those of the ceramics fabricated from $Si_3N_4-Si_2O_7$ compositions. The $Si_3N_4-Re_4Si_2N_2O_7$composition investigated herein showed comparable high temperature strength to those from $Si_3N_4-Re_2Si_2O_7$ compositions. Si3N4 ceramics from a $Si_3N_4-Y_4Si_2N_2O_7$ composition showed the highest strength of 877 MPa at $1200^{\circ}C$ among the compositions. All $Si_3N_4$ ceramics investigated herein showed a parabolic weight gain with oxidation time at $1400^{\circ}C$ and the oxidation products of the ceramics were $SiO_2$ and $Re_2Si_2O_7$. The $Si_3N_4-Re_4Si_2N_2O_7$ compositions showed inferior oxidation resistance to those from $Si_3n_4-Re_2Si_2O_7$ compositions, owing to the incompatibility of the secondary crystalline phases of those ceramics with $SiO_2$, the oxidation product of Si3N4.Si3N4 ceramics from a $Si_3N_4-Er_4Si_2N_2O_7$ composition showed the best oxidation resistance of 0.375mg/$\textrm{cm}^2$ after oxidation at $1400^{\circ}C$ for 102 h in air among the compositions.

• Journal of the Korean Vacuum Society
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• v.17 no.5
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• pp.426-434
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• 2008

A space averaged $SiH_4/O_2/Ar$ simulator for the high density inductively coupled plasma sources for $SiH_4/O_2/Ar$ discharge is developed. The developed simulator uses space averaged fluid equations for electrons, positive ions, negative ions, neutral species, and radicals in $SiH_4/O_2/Ar$ plasma discharge, and the electron heating model including the anomalous skin effect. Using the developed simulator, the dependency of the density of charged particles, neutral particles, and radicals, the electron temperature, the plasma resistance, and the power absorption coefficient for the RF power and pressure is calculated.

• The Journal of Natural Sciences
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• v.5 no.2
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• pp.75-80
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• 1992

The objective of this study is to investigate the effect of dispersion of silicon nitride powder with 5wt% $A1_2$$O_3$ and 5wt% $Y_2$$O_3$ on the microstructure of a sintered body. $Si_3$$N_4$ powder was dispered in a distilled water with varing pH.Zeta potential was measured and the dispersion states were directly observed by SEM. Green bodies were obtained by slip-casting and fired at $1750^{\circ}C$ for 1 hr. Microstructures of fired specimens were observed by SEM. The result were that the specimen prepared from the dispersions with pH 5 and 10 showed the best densification.

• Journal of the Korean Ceramic Society
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• v.34 no.7
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• pp.774-780
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• 1997

Porous low reflective coating films of SiO2.ZrO2 system were prepared from the mixed alkoxide solutions of Zr(O-nC3H7)4 and partially prehydrolyzed TEOS by the sol-gel method using the dip-coating technique. In the case of 90SiO2.10ZrO2 porous coating films with HCl and H2O content was 0.3 mole and 4 mole, 378 m2/g of the specific surface area, 0.254 cm3/g of total pore volume, 30-50$\AA$ of average pore diameter. The transmittance of 90SiO2.10ZrO2 porous coated films was 95.38% at the wavelength of 550 nm, compared with the parent glass, the transmittance was increased with 4.38%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.576-581
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• 2005

In this paper. the a-Si:H TFT using ferroelectric of $SrTiO_3$ as a gate insulator is fabricated on glass. High k gate dielectric is required for on-current, threshold voltage and breakdown characteristics of TFT Dielectric characteristics of ferroelectric are superior to $SiO_2$ and $Si_3N_4$. Ferroelectric increases on-current and decreases threshold voltage of TFT and also ran improve breakdown characteristics.$SrTiO_4$ thin film is deposited by e-beam evaporation. Deposited films are annealed for 1 hour in N2 ambient at $150^{\circ}C\~600^{\circ}C$. Dielectric constant of ferroelectric is about 60-100 and breakdown field is about IMV/cm. In this paper, the TFT using ferroelectric consisted of double layer gate insulator to minimize the leakage current. a-SiN:H, a-Si:H (n-type a-Si:H) are deposited onto $SrTiO_3$ film to make MFNS(Metal/ferroelectric/a-SiN:H/a-Si:H) by PECVD. In this paper, TFR using ferroelectric has channel length of$8~20{\mu}m$ and channel width of $80~200{\mu}m$. And it shows that drain current is $3.4{\mu}A$at 20 gate voltage, $I_{on}/I_{off}$ is a ratio of $10^5\~10^8,\;and\;V_{th}$ is$4\~5\;volts$, respectively. In the case of TFT without having ferroelectric, it indicates that the drain current is $1.5{\mu}A$ at 20gate voltage and $V_{th}$ is $5\~6$ volts. If properties of the ferroelectric thin film are improved, the performance of TFT using this ferroelectric thin film can be advanced.

• Journal of Power System Engineering
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• v.21 no.2
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• pp.14-19
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• 2017

The corrosion characteristics of Al-Si-Mg alloy were investigated in $O_2$ and $H_2S/H_2$ environments at high temperature. The weight gain and the reaction rate constant of the Al-Si-Mg alloy were measured in the oxygen and hydrogen sulfide environments at 773K. The weight gain of Al-Si-Mg alloy was showed parabolic increase in the oxygen and hydrogen sulfide environments. The reaction rate constants were confirmed to be $1.45{\times}10^{-4}mg^2cm^{-4}sec^{-2}$ in the oxygen environment and $6.19{\times}10^{-4}mg^2cm^{-4}sec^{-2}$ in the hydrogen sulfide environment respectively. As a result of XPS analysis on the specimen surface, $Al_2O_3$ and MgO compounds were detected in oxygen environment and $Al_2(SO_4)_3$ sulfate was detected in the hydrogen sulfide environment. Corrosion rate of Al-Si-Mg alloy was about 4.3 times faster in hydrogen sulfide environment than oxygen environment.

• Journal of the Korean Chemical Society
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• v.44 no.1
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• pp.60-67
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• 2000

The wavelength of the surface plasmon absorption depends on the dielectric matrix. $TiO_2/SiO_2$ complex oxide films doped with Au nanoclusters were prepared by sol-gel spin-coating method using $Ti(OPr^i)_4$, $Si(OEt)_4$, and $HAuCl_4{\cdot}7H_2O$. The wavelength of the maximum absorption of Au nanoehrsters in the $TiO_2/SiO_2$ thin films was obtained with lineality from 540 nm to 615 nm depending on the molar ratio of $TiO_2$. The particle sizes and structures of these nanoclusters have been identified through a TEM and X-ray diffraction patterns. The dielectric constants of $TiO_2/SiO_2$ thin films were calculated from the experimental results.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.7
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• pp.293-297
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• 2003

Silicon dioxide (SiO$_2$) layers were fabricated on Si$_3$N$_4$/SiO$_2$/Si layer structures by low pressure chemical vapor deposition (LPCVD). Potassium and aluminum were then coimplanted by implanting potassium ions with the energy of 100 ［keY］ and dose of 5x10$^{16}$ [cm￣$^2$］ and 1x10$^{17}$ [cm￣$^2$］ into an aluminum buffer layer on the SiO$_2$Si$_3$N4/SiO$_2$/Si structure. The pH, pNa, and pK ion sensitivities of the resulting layers were investigated and compared to those of as-deposited silicon dioxide layer. The pK-sensitivity of the silicon dioxide was enhanced by the K and Al coimplantation. On the contrary, the pH and pNa-sensitivities of the coimplanted silicon dioxides were quite lower than that of the as-deposited silicon dioxide.

• Journal of the Korean Ceramic Society
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• v.28 no.2
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• pp.130-140
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• 1991

The powders of the system Si3N4-Y2O3-AlN were prepared using Si(OC2H5)4 and YCl3.6H2O together with commercial AlN powder. $\alpha$-Si3N4 was prepared by the carbothermal reduction and nitridation of the hydrolyzed gel at 135$0^{\circ}C$ for 10h in N2 atmosphere. YCl3.6H2O was observed to be changed to Y2O3 during the reaction. $\alpha$-Sialon(X=0.2, 0.4, 0.6) ceramics were obtained by hot-pressing the Si3N4-Y2O3-AlN mixture at 178$0^{\circ}C$ for 1h under 30 MPa. The content of $\alpha$-Sialon increased with increasing metal solubility(x value) and $\alpha$-Sialon single phase was obtained at the metal solubility of 0.6. With increasing metal solubility, flexural strength, fracture toughness and thermal shock resistence were decreased, while the microhardness was increased. Large elongated $\beta$-Si3N4 grains were mainly observed at lower metal solubility. Mechanical prorerties of the sintered ceramics with X=0.2 were measured as follows : flexural strength ; 650 MPa, fracture toughness ; 3.63 MN/m3/2, hardness ; 14.7 GPa, thermal shock resistence temperature ; 58$0^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.41 no.3
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• pp.197-201
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• 2004

SiO$_2$ and SiON thick films were deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) technique on silicon wafer (100) using SiH$_4$ and $N_2$O as precursor gases. In this work, the influence of rf power, and rf bias power on the optical and physical properties of SiO$_2$ and SiON thick films is presented. The refractive index decreases with increasing rf power, and rf bias power. The refractive index of the films varied from 1.4493 to 1.4952 at wavelength at 1552 nm, with increasing rf power, the nitrogen content decreases while the oxygen content increases, in a manner that the O/N ratio increases approximately linearly.