• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.1
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• pp.6-12
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• 2013

Aerosol deposition(AD) coating that enable fabricate films at low temperature have begun to be widely researched for the integration of ceramics as well to realize high-speed deposition rates. For application of ceramic thick film by AD to display and electronic ceramic industry, fabrication of dense structure with a no cracking is required. In this study, to fabricate dense ceramic thick film, the effect of crystal phase of starting powder was investigated. For this study, amorphous and crystalline $SiO_2$ powders were used as starting powders. Two types of $SiO_2$ powders were deposited on glass substrate by AD. In the case of amorphous $SiO_2$ powder, the deposited films had extremely incompact and opaque layer, irrespective of particle size. In contrast to amorphous powder, in the case of crystalline powder, porous structure layer and dense microstructure with no cracking layer were fabricated depending on the particle size. The optimized starting powder size for dense coating layer was $1{\sim}2{\mu}m$. The transmittance of film reached a maximum of 76% at 800 nm.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.58.1-58.1
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• 2010

We have developed a novel crystallization process, where the crystallization temperature is lowered compared to the conventional RTA process and the metal contamination is lowered compared to the conventional VIC process. A very-thin a-Si film was deposited and crystallized at $550^{\circ}C$ for 3 h by the VIC process and then a thick a-Si film was deposited and crystallized by the RTA process at $680^{\circ}C$ for 5 min using the VIC poly-Si layer as a crystallization seed layer. The RTA crystallized temperature could be lowered up to $50^{\circ}C$, compared to RTA process alone. The poly-Si film appeared a needle-like growth front and relatively well-arranged (111) orientation. In addition, the Ni concentration in the poly-Si film was lowered to $3{\times}10^{17}\;cm^{-3}$ and that at the poly-Si/$SiO_2$ interface was lowered to $5{\times}10^{19}\;cm^{-3}$. The reduction in metal contamination could be greatly helpful to achieve a low leakage current in poly-Si TFT, which is the critical parameter for commercialization of AMOLED.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.6-8
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• 2005

The optical and electrical properties of indium tin oxide (ITO) thin films deposited at room temperature can be substantially enhanced by adopting a two-step process. In the first step, the films (50 nm thick) were grown by pulsed laser deposition (PLD) on glass substrate at room temperature and quickly annealed at $400^{\circ}C$ in nitrogen ambient for 1 minute by using rapid thermal annealing method. The process was completed by additional deposition (150 nm thick) on annealed film at room temperature. High quality ITO films grown by two-step process at room temperature could be obtained with the resistivity of $3.02{\times}10^{-4}{\Omega}cm$, the carrier mobility of 32.07 $cm^2/Vs$, and the transparency above 90 % in visible region mainly due to the enhancement of the film crystallinity and the increase of grain size.

• Korean Journal of Materials Research
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• v.33 no.7
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• pp.309-314
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• 2023

This study aimed to address the limitations of traditional plasma nitriding methods by implementing a short-term plasma oxy-nitriding treatment on the surface of AISI 420 martensitic stainless steel. This treatment involved the sequential formation of nitride and oxide layers, to enhance surface hardness and corrosion resistance, respectively. The process resulted in the formation of a 20 ㎛-thick nitride layer and a 3 ㎛-thick oxide layer on the steel surface. Initially, the hardness increased by 2.2 times after nitriding, followed by a subsequent decrease of approximately 31 % after oxidation. While the nitriding process reduced corrosion resistance, the subsequent oxidation process led to the formation of a passive oxide film, effectively resolving this issue. The pitting corrosion of the oxide passive film started at 82.6 mVssc, providing better corrosion resistance characteristics than the nitride layer. Consequently, the trade-off between surface hardness and corrosion resistance in plasma oxy-nitrided AISI 420 martensitic stainless steel is anticipated to be recognized as an innovative and comprehensive surface treatment process for biomedical components.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.262-264
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• 2005

$Bi_{2}Sr_{2}CaCu_{2}O_{x}$(Bi-2212) and $Bi_{2}Sr_{2}Ca_{2}Cu_{3}O_{y}$(Bi-2223) high-$T_{c}$ superconductor(HTS) coating have been prepared by plasma spraying and heaat treatment. The Bi-2212 HTS coating later is synthesized through the peritectic reaction between Sr-Ca-Cu oxide coating layer and Bi-Cu oxide coating later, and $Bi_{2}Sr_{2}CaCu_{2}O_{y}$(Bi-2212) superconducting phase grow by partial melting process. The superconducting characteristic depends strongly on the conditions of the partial melting process. the Bi-2212 HTS layer consists of the whiskers grown in the diffusion direction. Above the 2212 layer, Bi-2223 phase and secondary phase was observed. The secondary phase is distributed uniformly over the whole surface. This is caused to the microcrack on the coatings surface. Despite everything, the film shows superconducting with an onset $T_{c}$ of about 115K. There are two changes steps. One changes (1step) at 115K is due to the diamagnetism of the Bi-2223 phase and the other changes (2step) at 78K is due to the diamagnetism of the Bi-2212 phase.

• Korean Journal of Materials Research
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• v.15 no.3
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• pp.149-154
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• 2005

Teflon like fluorocarbon thin films have been deposited on silicon and oxide molds as an antistiction layer for the hot embossing process by an inductively coupled plasma (ICP) chemical vapor deposition (CVD) method. The process was performed at $C_4F_8$ gas flow rate of 2 sccm and 30 W of plasma power as a function of substrate temperature. The thickness of film was measured by a spectroscopic ellipsometry. These films were left in a vacuum oven of 100, 200 and $300^{\circ}C$ for a week. The change of film thickness, contact angle and adhesion and friction force was measured before and after the thermal test. No degradation of film was observed when films were treated at $100^{\circ}C$. The heat treatment of films at 200 and $300^{\circ}C$ caused the reduction of contact angles and film thickness in both silicon and oxide samples. Higher adhesion and friction forces of films were also measured on films treated at higher temperatures than $100^{\circ}C$. No differences on film properties were found when films were deposited on either silicon or oxide. A 100 nm silicon template with 1 to $500\;{\mu}m$ patterns was used for the hot embossing process on $4.5\;{\mu}m$ thick PMMA spun coated silicon wafers. The antistiction layer of 10 nm was deposited on the silicon mold. No stiction or damages were found on PMMA surfaces even after 30 times of hot embossing at $200^{\circ}C$ and 10 kN.

• Journal of Information Display
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• v.4 no.2
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• pp.1-6
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• 2003

In this paper, we demonstrate that the organic electrophosphorescent device is driven by the organic thin film transistor with spin-coated photoacryl gate insulator. It was found that electrical output characteristics in our organic thin film transistors using the staggered-inverted top-contact structure showed the non-saturated slope in the saturation region and the sub-threshold nonlinearity in the triode region, where we obtained the maximum power luminance that was about 90 $cd/m^2$. Field effect mobility, threshold voltage, and on-off current ratio in 0.45 ${\mu}m$ thick gate dielectric layer were 0.17 $cm^2/Vs$, -7 V, and $10^6$ , respectively. In order to form polyimide as a gate insulator, vapor deposition polymerization process was also introduced instead of spin-coating process, where polyimide film was co-deposited by high-vacuum thermal evaporation from 4,4'-oxydiphthalic anhydride (ODPA) and 4,4'-oxydianiline (ODA) and cured at 150${\sqsubset}$for 1hr. It was also found that field effect mobility, threshold voltage, on-off current ratio, and sub-threshold slope with 0.45 ${\mu}m$ thick gate dielectric films were 0.134 $cm^2/Vs$, -7 V, and $10^6$ A/A, and 1 V/decade, respectively.

• Journal of the Korean institute of surface engineering
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• v.42 no.5
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• pp.216-219
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• 2009

A surface acoustic wave (SAW) filter structure was fabricated employing $4{\mu}m$ thick nanocrystalline diamond (NCD) and $2.2{\mu}m$ thick ZnO films on Si wafer. The NCD film was deposited in an $Ar/CH_4$ gas mixture by microwave plasma chemical vapor deposition method. The ZnO film was formed over the NCD film in an RF magnetron sputter using ZnO target and $Ar/O_2$ gas. On the top of the two layers, copper film was deposited by the RF sputter and inter digital transducer (IDT) electrode pattern (line/space : $1.5/1.5{\mu}m$) was defined by the photolithography including a lift-off etching process. The fabricated SAW filter exhibited the center frequency of 1.66 GHz and the phase velocity of 9,960 m/s, which demonstrated that a giga Hertz SAW filter can be realized by utilizing the nanocrystalline diamond thin film.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.6
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• pp.239-244
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• 2015

Lead zirconate titanate (PZT) thick films with thickness of $10{\sim}20{\mu}m$ were fabricated on silicon substrate by aerosol deposition method. As-deposited films on silicon were annealed at the temperatures of $700^{\circ}C$. The electrical properties of films deposited by PZT powders were characterized using impedance analyzer and Sawyer-Tower circuit. The PZT powder was prepared by both conventional solid reaction process and sol-gel process. The remanent polarization, coercive field, and dielectric constant of the $10{\mu}m$ thick film with solid reaction process were $20{\mu}C/cm^2$, 30 kV/cm and 1320, respectively. On the other hand, the PZT films by sol-gel process showed a poor dielectric constant of 635. The reason was probably due to the presence of pores produced from organic residue during annealing.

• Transactions on Electrical and Electronic Materials
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• v.5 no.4
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• pp.158-160
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• 2004

BiSrCaCuO thick films were fabricated by plasma enhanced chemical vapor deposition, and the crystallinity and the superconducting properties were investigated. The superconductivity was achieved at 20 K with an onset temperature of around 90 K in the film prepared at 72$0^{\circ}C$. From X ray diffraction analysis, the main superconducting phase in the films was the low Tc phase at 700∼75$0^{\circ}C$ and the high Tc phase at 750 ∼ 80$0^{\circ}C$.