• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.51-56
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• 2001

$CeO_2$ thin films as insulator for MFISFET (Metal-ferroelectric-insulator- semiconductor-field effect transistor) were deposited by r.f. magnetron sputtering. Ar and $O_2$ gas as the deposition gas were used and the effects of oxygen partial pressure during sputtering on texture and electrical properties of $CeO_2$ thin films were evaluated. All $CeO_2$ thin films deposited on p-type Si(100) substrate at $600^{\circ}C$ exhibited (200) preferred orientation. The films deposited with only Ar gas among various condition had highest preferred orientation but show large hysteresis characteristics in capacitance-voltage measurement due to relatively many charged paricles and roughness. Films show smooth surface state and good C-V characteristics with increasing oxygen partial pressure. It was thought that this trend in C-V characteristics was due to the amount of mobile ionic charge within $CeO_2$ films. The composition of films show oxygen excess, that is, O/$Ce_2$ ratio of films was 2.22~2.42 range and leakage current of films show $10^{-7}~10^{-8}A$order at 100 kV/cm.

• Progress in Superconductivity
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• v.11 no.1
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• pp.25-29
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• 2009

Polycrystalline samples of $(R_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ (R = Lu and Y) were synthesized by a solid-state reaction route, and the phase stabilities were examined by heating at temperatures between $800^{\circ}C$ and $900^{\circ}C$ in various atmospheres. A comparative analyses of the x-ray diffraction data of the $(Lu_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ and $(Y_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ compounds showed that the 123 phase of both compounds is stable under heating in air and $O_2$ of 1 atm. However, contrary to the $(Y_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ compound, the $(Lu_{0.8}Ca_{0.2})Ba_2Cu_3O_z$ compound was found to become unstable when heated in the low oxygen partial pressure below about 8 % $O_2\;in\;N_2$, Considering the instability of parent $LuBa_2Cu_3O_z$ compound, this result suggests that the phase stability of Lu-based 123 compounds is sensitive to both the composition and the oxygen partial pressure.

• Corrosion Science and Technology
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• v.16 no.1
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• pp.15-22
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• 2017

An oxidation-reduction scheme is an alternative approach for improving the galvanizability of advanced high-strength steel in the continuous hot-dip galvanizing process. Here, we investigated the effect of oxygen partial pressure ($P_{O_2}$) on the oxidation behavior of a transformation-induced plasticity steel containing 1.5 wt% Si and 1.6 wt% Mn during heating to and holding for 60 s at $700^{\circ}C$ under atmospheres with various $P_{O_2}$ values. Irrespective of $P_{O_2}$, a thin amorphous Si-rich layer of Si-Mn-O was formed underneath the Fe oxide scale (a $Fe_2O_3/Fe_3O_4$ bilayer) in the heating stage. In contrast to Si, Mn tended to segregate at the scale surface as $(Fe,Mn)_2O_3$. The multilayered structure of $(Fe,Mn)_2O_3/Fe_2O_3/Fe_3O_4$/amorphous Si-Mn-O remained even after extended oxidizing at $700^{\circ}C$ for 60 s. $Fe_2O_3$ was the dominantly growing oxide phase in the scale. The enhanced growth rate of $Fe_2O_3$ with increasing $P_{O_2}$ resulted in the formation of more Kirkendall voids in the amorphous Si-rich layer and a less Mn segregation at the scale surface. The mechanisms underlying the absence of FeO and the formation of Kirkendall voids are discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.191-191
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• 2009

$Bi_4Ti_3O_{12}$ (BiT) thin films were well developed on the Pt/Ti/$SiO_2/Si$ substrate by a metal organic decomposition (MOD) method. Oxygen was effective on the crystallization of the BiT thin films during a rapid thermal annealing process. The electrical properties of the BiT films dependant on the oxygen partial pressure were investigated. No crystalline phase was observed for the BiT film annealed at $700^{\circ}C$ under oxygen free atmosphere. However, its crystallinity was significantly evolutionned with increasing oxygen partial pressure. In addition, its dielectric and piezoelectric properties were enhanced with increasing oxygen partial pressure to 10 torr. Especially, the BiT film, annealed at $700^{\circ}C$ and 10 torr oxygen pressure, showed good dielectric properties: dielectric constant of 51 and dielectric loss of 0.2 % at 100 kHz. Its leakage current and piezoelectric constant ($d_{33}$) was also considerably improved, being as 0.62 nA/$cm^2$ at 1 V and approximately 51 pm/V, respectively.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.44 no.8
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• pp.1063-1067
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• 1995

The superconducting properties of YBa$_{2}$Cu$_{3}$$O_{7-x}$(YBaCuO) thin films prepared by laser ablation have been investigated. The x-ray diffraction patterns and surface morphology of the films were substantially different from one another. The compositional ratios of YBaCuO films were controlled by the conditions of the target-substrate distance. The YBaCuO films manufactured on MgO(100) substrate were indicated T$_{c}$(zero)=91.2 K, T$_{c}$(onset)=93 K, and J$_{c}$=3.5*10$^{5}$ A/cm$^{2}$(at 77.3K). The optimum conditions were found to be a substrate temperature of 710 .deg. C, a energy density of 2 J/cm$^{2}$, and a target-substrate distance of 60 mm in an oxygen partial pressure of 200 mTorr.0 mTorr.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.93-94
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• 2009

The influences of $O_2$ partial pressure on electrical properties of transparent semiconducting indium zinc tin oxide thin films deposited at room temperature by magnetron sputtering have been investigated. The experimental results show that by varying the $O_2$ partial pressure during deposition, electron mobilities of IZTO thin film can be controlled between 7 and $25\;cm^2/Vs$. For conducting films, the carrier concentration and resistivity are ${\sim}\;10^{21}\;cm^{-3}$ and ${\sim}\;10^{-4}\;{\Omega}\;cm$, respectively. Concerning semiconducting films, under 12% $O_2$ partial fraction, the electron concentration is $10^{18}\;cm^{-3}$, showing the promising candidate for the application of transparent thin film transistors.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.78-78
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• 2013

Recently, many platinoid metals like platinum and ruthenium have been used as an electrode of microelectronic devices because of their low resistivity and high work-function. However the material cost of Ru is very expensive and it usually takes long initial nucleation time on SiO2 during chemical deposition. Therefore many researchers have focused on how to enhance the initial growth rate on SiO2 surface. There are two methods to deposit Ru film with atomic layer deposition (ALD); the one is thermal ALD using dilute oxygen gas as a reactant, and the other is plasma enhanced ALD (PEALD) using NH3 plasma as a reactant. Generally, the film roughness of Ru film deposited by PEALD is smoother than that deposited by thermal ALD. However, the plasma is not favorable in the application of high aspect ratio structure. In this study, we used a bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp)2] as a metal organic precursor for both thermal and plasma enhanced ALDs. In order to reduce initial nucleation time, we use several methods such as Ar plasma pre-treatment for PEALD and usage of sacrificial RuO2 under layer for thermal ALD. In case of PEALD, some of surface hydroxyls were removed from SiO2 substrate during the Ar plasma treatment. And relatively high surface nitrogen concentration after first NH3 plasma exposure step in ALD process was observed with in-situ Auger electron spectroscopy (AES). This means that surface amine filled the hydroxyl removed sites by the NH3 plasma. Surface amine played a role as a reduction site but not a nucleation site. Therefore, the precursor reduction was enhanced but the adhesion property was degraded. In case of thermal ALD, a Ru film was deposited from Ru precursors on the surface of RuO2 and the RuO2 film was reduced from RuO2/SiO2 interface to Ru during the deposition. The reduction process was controlled by oxygen partial pressure in ambient. Under high oxygen partial pressure, RuO2 was deposited on RuO2/SiO2, and under medium oxygen partial pressure, RuO2 was partially reduced and oxygen concentration in RuO2 film was decreased. Under low oxygen partial pressure, finally RuO2 was disappeared and about 3% of oxygen was remained. Usually rough surface was observed with longer initial nucleation time. However, the Ru deposited with reduction of RuO2 exhibits smooth surface and was deposited quickly because the sacrificial RuO2 has no initial nucleation time on SiO2 and played a role as a buffer layer between Ru and SiO2.

• Bulletin of the Korean Chemical Society
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• v.15 no.1
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• pp.33-36
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• 1994

The x values of nonstoichiometric chemical formula, $Tb_4O_{7-{\delta}}\;or\;TbO_{1.5+x}$, have been determined in temperature range from 600$^{\circ}$C to 1000$^{\circ}$C under oxygen partial pressure of 2 ${\times}$ 10$^{-1}$ to 1 ${\times}$ 10$^{-5}$ atm by using quartz microbalance. The x values varied from 0.0478 to 0.1964 in the above conditions. The enthalpy of formation for x' in TbO$_{1.5+(0.25-xo-x')}$, ${\delta}H_f$, was 4.93-3.40 kcal mol$^{-1}$ and the oxygen partial pressure dependence was -1/8.80∼-1/11.8 under these conditions. The electrical conductivity of the $TbO_{1.5+x}$ was measured under the same conditions and the values varied from about 10$^{-3}$ to 10$^{-6}\;{\Omega}^{-1}cm^{-1}$ within semiconductor range. The activation energies for the conduction increase with oxygen partial pressure from 0.83 to 0.89 eV under the above conditions. The l/n values obtained from the oxygen pressure dependence of the conductivity are 1/4.4-1/5.2. The conduction mechanism, defect structure, and other physical properties of the oxides are dicussed with the x values, the electrical conductivity values, and the thermodynamic data.

• Journal of the Korean Ceramic Society
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• v.37 no.8
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• pp.817-823
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• 2000

A solid-state electrochemicall cell for sensing CO2 gas was fabricated using a solid electrolyte of Li2CO3-Li3PO4-Al2O3 mixture and a reference electrode of LiMn2O4. The e.m.f. (electromotive force) of sensor showed a good accordance with theoretical Nernst slope (n=2) for CO2 gas concentration range of 100-10000 ppm above 35$0^{\circ}C$. The e.m.f. of sensor was constant regardless of oxygen partial pressure at the high temperature above 0.1 atm. It was, however, a little depended on oxygen partial pressure as the pressure decreased below 0.1 atm. The oxygen-dependency of our sensor gradually disappeared as the operating temperature increased. The sensing behavior of our CO2 sensor was affected by the presence of water vapor, but its effect was small comparing with other sensors.

• The Korean Journal of Ceramics
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• v.4 no.2
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• pp.68-71
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• 1998

The effect of Mn and Nb additions on the electrical properties of BaTiO$_3$ has been studied by means of equilibrium electrical conductivity as a function of temperature, oxygen partial pressure(Po$_2$) and composition. If the manganese ion is added to the normal Ti site, i.e. BaTi$_{1-x}Mn_xO_{\delta-6}$, the equilibrium conductivity shows strong evidence of acceptor-doped behavior. The conductivity minimum, corresponding to the transition from oxygen excess, p-type behavior to oxygen deficient, n-type behavior with decreasing Po$_2$, is displaced to lower Po$_2$ and is broadened and flattened. The partial replacement of Mn ion with Nb decreases the acceptor-doped effect and the total replacement exhibits a typical donor-doped behavior. It was confirmed that unlike undoped or other acceptor-doped behavior. It was confirmed that unlike undoped or other acceptor-doped samples, for the p-type region, the electrical conductivity follows the 1/6th power dependence of oxygen partial pressure.