• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.4
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• pp.327-332
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• 2009

In the devices structure of ITO/N,N'-diphenyl-N,N' bis (3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD) /tris (8-hydroxyquinoline)aluminum$(Alq_3)$electron-transport-layer(ETL)(2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline(BCP))/Al, we have studied the efficiency improvement of organic light-emitting diodes depending on the thickness variation of BCP using electron transport layer. The thickness of TPD and $Alq_3$ was manufactured 40 nm, 60 nm under a base pressure of $5{\times}10^{-6}$ Torr using at thermal evaporation, respectively. The TPD and $Alq_3$ layer were evaporated to be deposition rate of $2.5{\AA}/s$. And the BCP was evaporated to be a4 a deposition of $1.0{\AA}/s$. As the experimental results, we found that the luminous efficiency and the external quantum efficiency of the device is superior to others when thickness of BCP is 5 nm. Also, operating voltage is lowest. Compared to the ones from the devices without BCP layer, the luminous efficiency and the external quantum efficiency were improved by a factor of four hundred ninty and five hundred, respectively. And operating voltage is reduced to about 2 V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.275-276
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• 2005

Organic Light Emitting Diodes(OLEDs) are attractive as alternative display components because of their relative merits of being self-emitting, having large intrinsic viewing angle and fast switching speed. But because of their relatively short history of development, much remains to be studied in terms of their basic device physics and design, manufacturing techniques, stability and so on. We invested electrical properties of N,N-diphenyl-N,N bis (3-methyphenyl)-1,1'-biphenyl-4,4'-diamine(TPD) and tris-8-hydroxyquinoline aluminum($Alq_3$) when their thicknesses were changed variedly from 3:7 to 7:3 of their thickness ratios. And we also studied properties of OLEDs depend on their deposition rate between 0.05$\sim$0.2 [nm/s].

• Korean Journal of Materials Research
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• v.18 no.10
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• pp.535-541
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• 2008

Growth behavior of InGaN/GaN self-assembled quantum dots (QDs) was investigated with respect to different growth parameters in low pressure metalorganic chemical vapor deposition. Locally formed examples of three dimensional InGaN islands were confirmed from the surface observation image with increasing indium source ratio and growth time. The InGaN/GaN QDs were formed in Stranski-Krastanow (SK) growth mode by the continuous supply of metalorganic (MO) sources, whereas they were formed in the Volmer-Weber (V-W) growth mode by the periodic interruption of the MO sources. High density InGaN QDs with $1{\sim}2nm$ height and $40{\sim}50nm$ diameter were formed by the S-K growth mode. Dome shape InGaN dots with $200{\sim}400nm$ diameter were formed by the V-W growth mode. InN content in InGaN QDs was estimated to be reduced with the increase of growth temperature. A strong peak between 420-460 nm (2.96-2.70 eV) was observed for the InGaN QDs grown by S-K growth mode in photoluminescence spectrum together with the GaN buffer layer peak at 362.2 nm (3.41 eV).

• Journal of the Korean Vacuum Society
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• v.17 no.3
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• pp.220-225
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• 2008

In this research, the P(VDF-TrFE) copolymer thin films were prepared by the physical vapor deposition and studied to their piezoelectric properties. In the case of a specimen produced by varying the deposition temperature from $260^{\circ}C$ to $300^{\circ}C$, its piezoelectric coefficient($d_{33}$) increased from 32.3pC/N to 36.28pC/N, and piezoelectric voltage coefficient($g_{33}$) from $793{\times}10^{-3}V{\cdot}m/N$ to $910.5{\times}10^{-3}V{\cdot}m/N$. On the basis of these experimental results, we concluded that the P(VDF-TrFE) copolymer thin film prepared at $300^{\circ}C$ showed the optimum piezoelectric properties. At the deposition temperature of $320^{\circ}C$, its piezoelectric coefficient(d33) decreased 25.3 pC/N and piezoelectric voltage coefficient($g_{33}$) $680{\times}10^{-3}V{\cdot}m/N$.

• Journal of the Korean Society for Heat Treatment
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• v.3 no.1
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• pp.17-24
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• 1990

In this study, TiN film was deposited onto steel by R.F.-PACVD in order to investigate the influence of parameters on the adhesion strength between film and substrate. Experimental results showed that adhesion strength by SAT is different from by optical microscopy. Adhesion strength is increased when the deposition temperature increases and is influenced by R.F. power and electrode distance. Especially heat treatment on the substrate has influenced over the adhesion strength, so it showed the 22 Newtons in adhesion strength by SAT and adhesion strength is decreased when deposition thickeness is thick and hardness is high. Also if the film is thick and high hardness simultaneous, the film was delaminated seriously.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.7
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• pp.760-765
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• 1992

The material properties and the TFT characteristics fabricated on SiOS12T substrate by LPCVD using SiHS14T gas were investigated. The deposition rate showed Arrhenius behavior with an activation energy of 31Kcal/mol. And the transition temperature form amorphous to crystalline deposition was observed at 570$^{\circ}C$-580$^{\circ}C$. The strong(220) texture was observed as the deposition temperature increases. XRD analysis showed that the film texture of the as-deposited polycrystalline silicon does not change after annealing at 850$^{\circ}C$. The fabricated TFT's based on the as-deposited amorphous film showed superior electrical characteristics to those of the as-deposited polycrystalline films. It is considered that the different electrical characteristics result from the difference of flat band voltage(VS1FBT) due to the interface trap density between the gate oxide and the active channel.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.13-16
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• 2000

(PbS)$_{1-x}$ -(CuS)$_{x}$ thin films(x=0, 0.5, 1) were grown on glass substrates by using a chemical bath deposition method. The molecular ratio of Pb to Cu for the PbS-CuS thin films(x=0.5) was measured about 7:3 by using EDX and XRF. The resistivity of non-annealed (PbS)$_{1-x}$ -(CuS)$_{x}$ thin films was about 10 $\Omega$ . cm. However, after annealing, the resistivity of PbS showed a little change, while PbS-CuS and CuS significantly decreased in the range of 0.002 to 0.005$\Omega$.cm. PbS was p-type and CuS was n-type.-type.

• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.134-139
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• 1998

Amorphous fluorocarbon (a-C:F) is of interest for low dielectric interlayer material, but in this work we applied this material to FED field emitter. N-doped a-C:F films were deposited by inductively coupled plasma chemical vapor deposition (ICPCVD). The Raman spectra were measured to study the film structure and inter-band optical absorption coefficients were measured using Perkin-Elmer UV-VIS-IR spectrophotometer and optical band gap was obtained using Tauc's plot. XPS spectrum and AFM image were investigated to study bond structure and surface morphology. Current-electric field(I-E) characteristic of the film was measured for the characterization of electron emission properties. The optimum doping concentration was found to be [N2]/[CF4]=9% in the gas phase. The turn-on field and the emission current density at $[N_2]/[CF_4]$=9% were found to be 7.34V/$\mu\textrm{m}$ and 16 $\mu\textrm{A}/\textrm{cm}^2$ at 12.8V/$\mu\textrm{m}$, respectively.

• Journal of the Korean Vacuum Society
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• v.6 no.S1
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• pp.154-159
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• 1997

The crystal structure properties of TiN thin films deposited on SKD61 steel and Si(100) substrates by Ion Beam Assisted Deposition have been studied to clarify the thin film growth mechanism by using XRD, RBS, SEM, and AFM. The preferred orientation of TiN thin films changes from (111) to (100) as increasing the assisted energy. This tendency is independent of the substrate structure. The TiN thin film grow with (100) direction having surface free energy minimum as the assisted energy increases.

• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.597-609
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• 2020

Accident Tolerant Fuels have been widely studied since the Fukushima-Daiichi accident in 2011 as one of the options on how to further enhance the safety of nuclear power plants. Deposition of protective coatings on nuclear fuel claddings has been considered as a near-term concept that will reduce the high-temperature oxidation rate and enhance accidental tolerance of the cladding while providing additional benefits during normal operation and transients. This study focuses on experimental testing of Zr-based alloys coated with Cr-based coatings using Physical Vapour Deposition. The results of long-term corrosion tests, as well as tests simulating postulated accidents, are presented. Zr-1%Nb alloy used as nuclear fuel cladding serves as a substrate and Cr, CrN, Cr_xN_y layers are deposited by unbalanced magnetron sputtering and reactive magnetron sputtering. The deposition procedures are optimized in order to improve coating properties. Coated as well as reference uncoated samples were experimentally tested. The presented results include standard long-term corrosion tests at 360℃ in WWER water chemistry, burst (creep) tests and mainly single and double-sided high-temperature steam oxidation tests between 1000 and 1400℃ related to postulated Loss-of-coolant accident and Design extension conditions. Coated and reference samples were characterized pre- and post-testing using mechanical testing (microhardness, ring compression test), Thermal Evolved Gas Analysis analysis (hydrogen, oxygen concentration), optical microscopy, scanning electron microscopy (EDS, WDS, EBSD) and X-ray diffraction.