• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.252.1-252.1
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• 2013

Hexagonal boron nitride (h-BN) is a two dimensional material which has high band-gap, flatness and inert properties. This properties are used various applications such as dielectric for electronic device, protective coating and ultra violet emitter so on. 1) In this report, we were growing h-BN sheet directly on sapphire 2"wafer. Ammonia borane (H3BNH3) and nickel were deposited on sapphire wafer by evaporate method. We used nickel film as a sub catalyst to make h-BN sheet growth. 2) During annealing process, ammonia borane moved to sapphire surface through the nickel grain boundary. 3) Synthesized h-BN sheet was confirmed by raman spectroscopy (FWHM: ~30cm-1) and layered structure was defined by cross TEM (~10 layer). Also we controlled number of layer by using of different nickel and ammonia borane thickness. This nickel film supported h-BN growth method may propose fully and directly growing on sapphire. And using deposited ammonia borane and nickel films is scalable and controllable the thickness for h-BN layer number controlling.

• Korean Journal of Metals and Materials
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• v.49 no.10
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• pp.780-789
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• 2011

The effects of alloyed carbon on the pitting corrosion, the general corrosion, and the passivity behavior of Fe18Cr10Mn0.4NxC (x=0~0.38 wt%) alloys were investigated by various electrochemical methods and XPS analysis. The alloyed carbon increased the general corrosion resistance of the FeCrMnN matrix. Carbon enhanced the corrosion potential, reduced the metal dissolution rate, and accelerated the hydrogen evolution reaction rate in various acidic solutions. In addition, carbon promoted the pitting corrosion resistance of the matrix in a chloride solution. The alloyed carbon in the matrix increased the chromium content in the passive film, and thus the passive film became more protective.

• Journal of the Korean institute of surface engineering
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• v.27 no.3
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• pp.123-133
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• 1994

Oxidation behavior of STS 304 and 430, produced by POSCO, Korea, was studied in order to study the surface defects formed during manufacturing processes. Oxidation experiments were carried out in a preheat-ed furnace at 850~$1, 250^{\circ}C$ in air and in a simulated coke oven gas(COG) atmosphere. The reaction products were examined by XRD, SEM and EDX on their surfaces and cross sections. Protective $Cr_2O_3$-primary oxide film was formed initially, but at critical point this film was broken and a duplex scale consisting of $Fe_2O_3$- and Fe$Cr_2O_4$- was formed. It was more severely attacked in a simulated COG atmosphere than in air, and STS 304 was superior to STS 430 in oxidation resistance.

• Journal of the Korean Ceramic Society
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• v.32 no.1
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• pp.95-105
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• 1995

Ceria(CeO2) stabilized zirconia(CeSZ) sol was synthesized with zirconium n-butoxide Zr(OC4H9)4 and cerium nitrate hexahydrate Ce(NO3)3.6H2O as precursors and ethylacetoacetate(EAcAc) as a chelating agent under atmosphere. CeSZ films were deposited on AISI 304 stainless steel using the prepared polymeric sol by dipcoating and the coating characteristics were investigated by XRD, ellipsometry, scratch test and SEM. The CeSZ film began to crystallize from amorphous to tetragonal phase at 40$0^{\circ}C$ and it was not converted into monoclinic phase up to 100$0^{\circ}C$ by the addition of 16mol% CeO2 as a stabilizer which could suppress phase transformation of zirconia. The CeSZ films were prepared by varying the EAcAc contents and the cncentration of CeSZ sol and measured the thickness and refractive index. From these results, it was found that the EAcAc contents and concentration of CeSZ coating sol evidently affect the densification of CeSZ film. The CeSZ film coated with 0.4M CeSZ sol and heat-treated at $600^{\circ}C$ for 10min had thickness of 50nm and 17% porosity. The CeSZ film on 304 stainless steel effectively acted as a protective layer against oxidation up to 80$0^{\circ}C$ and had superior corrosion resistance in 25% H2SO4 solution for 4.5 hrs.

• Applied Chemistry for Engineering
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• v.2 no.4
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• pp.393-398
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• 1991

An experimental reactor system was devised and employed to examine catalytic coal gasification. A 4-kw tungsten halogen lamp heater combinded with a graphite sample basket coated with silicon nitride film made rapid heating and cooling possible. Also a small graphite cap on the thermocouple tip which located just beneath the sample basket helped remarkably to read real temperatures. Silicon nitride film on the basket and the cap showed very good protection against the reaction between graphite and oxidant gases during the experiments. The weight of specimen could be continuously measured without disturbance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.467-470
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• 2004

Diamond-Like Carbon (DLC) thin film is a semiconductor with high mechanical hardness, low friction coefficient, high chemical inertness, and optical transparency. DLC thin films have widespread applications as protective coatings and solid lubricant coatings in areas such as Hard Disk Drive (HDD) and Micro-Electro-Mechanical-Systems (MEMS). In this work, the wear characteristics of DLC thin films deposited on silicon substrates using a DC-magnetron sputtering system were analyzed. The wear tracks were measured with an Atomic Force Microscope (AFM). To identify the sp2 and sp3 hybridization of carbon bonds and other bonds Raman spectroscopy was used. The structural information of DLC thin films was obtained with Fourier transform infrared spectroscopy and wear tests were conducted by using a micro-pin-on-reciprocator tester. Results showed that the wear characteristics were dependent on the sputtering conditions. The wear rate could be correlated with the bonding state of the DLC thin film.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.4
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• pp.1-14
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• 1991

In PECVD(Plasma-Enhanced Chemical Vapor Deposition) process, titanium nitride is thin and its adhesion is poor for the protective coatings. Therefore it has been studied that intermediate layer forms between substrate and TiN thin film. Using R.F. plasma nitriding, nitride layer was first formed, then TiN thin film coated by PECVD. The chemical composition of the coatings has been characterized using AES, EDS and their crystallographic structure by means of XRD. Mechanical properties such as microhardness and film adhesion have also been determined by vickers hardness test, scratch test and indentation test. As a result, there was no difference in chemical composition and structure between the TiN deposition only and the composite of TiN deposition on nitrided steel. It was found that nitrided substrate increased the hardness of TiN coatings and was beneficial in preventing the plastic deformation in the substrate. Therefore the effective load bearing capacity of the TiN coatings on nitrided steel was increased and their adhesion was improved as well. According to the results of this study, the processes that lead to the formation of composite layers characterized by good working properties, i.e., high microhardness, adhesion and resistance to deformation.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.806-809
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• 2003

Ion-induced secondary electron emission coefficient $({\gamma})$. of the patterned MgO thin film with geometrical structures has been measured by ${\gamma}$ - FIB(focused ion beam) system. The patterned MgO thin film with geometrical structures has been formed by the mask (mesh of ${\sim}$ $10{\mu}m^{2})$ under electron beam evaporation method. It is found that the higher ${\gamma}$. has been achieved by the patterned MgO thin film than the normal ones without patterning.

• Korean Journal of Materials Research
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• v.18 no.5
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• pp.272-276
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• 2008

In submicron MOSFET devices, maintaining the ratio between the channel length (L) and the channel depth (D) at 3 : 1 or larger is known to be critical in preventing deleterious short-channel effects. In this study, n-type SOI-MOSFETs with a channel length of $0.1\;{\mu}m$ and a Si film thickness (channel depth) of $0.033\;{\mu}m$ (L : D = 3 : 1) were virtually fabricated using a TSUPREM-4 process simulator. To form functioning transistors on the very thin Si film, a protective layer of $0.08\;{\mu}m$-thick surface oxide was deposited prior to the source/drain ion implantation so as to dampen the speed of the incoming As ions. The p-type boron doping concentration of the Si film, in which the device channel is formed, was used as the key variable in the process simulation. The finished devices were electrically tested with a Medici device simulator. The result showed that, for a given channel doping concentration of $1.9{\sim}2.5\;{\times}\;10^{18}\;cm^{-3}$, the threshold voltage was $0.5{\sim}0.7\;V$, and the subthreshold swing was $70{\sim}80\;mV/dec$. These value ranges are all fairly reasonable and should form a 'magic region' in which SOI-MOSFETs run optimally.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3723-3729
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• 2010

We investigated the high-excitation voltage cathodoluminescence (CL) performance of blue light-emitting (ZnS:Ag,Al,Cl) and green light-emitting (ZnS:Cu,Al) phosphors coated with metal oxides ($SiO_2$, $Al_2O_3$, and MgO). Hydrolysis of the metal oxide precursors tetraethoxysilane, aluminum isopropoxide, and magnesium nitrate, with subsequent heat annealing at $400^{\circ}C$, produced $SiO_2$ nanoparticles, an $Al_2O_3$ thin film, and MgO scale-type film, respectively, on the surface of the phosphors. Effects of the phosphor surface coatings on CL intensities and aging behavior of the phosphors were assessed using an accelerating voltage of 12 kV. The MgO thick film coverage exhibited less reduction in initial CL intensity and was most effective in improving aging degradation. Phosphors treated with a low concentration of magnesium nitrate maintained their initial CL intensities without aging degradation for 2000 s. In contrast, the $SiO_2$ and the $Al_2O_3$ coverages were ineffective in improving aging degradation.