• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.2
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• pp.128-131
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• 2009

Silicon carbide (SiC) has attracted significant attention for high frequency, high temperature and high power devices due to its superior properties such as the large band gap, high breakdown electric field, high saturation velocity and high thermal conductivity. We performed Al ion implantation processes on n-type 4H-SiC substrate using a SILVACO ATHENA numerical simulator. The ion implantation model used Monte-Carlo method. We simulated the effect of channeling by Al implantation in both 0 off-axis and 8 off-axis n-type 4H-SiC substrate. We have investigated the effect of varying the implantation energies and the corresponding doses on the distribution of Al in 4H-SiC. The controlled implantation energies were 40, 60, 80, 100 and 120 keV and the implantation doses varied from $2{\times}10^{14}$ to $1{\times}10^{15}\;cm^{-2}$. The Al ion distribution was deeper with increasing implantation energy, whereas the doping level increased with increasing dose. The effect of post-implantation annealing on the electrical properties of Al-implanted p-n junction diode were also investigated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.2
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• pp.163-168
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• 2009

Hyperbranched conjugated polymers (p-HPPV and m-HPPV) with para and meta linkages were synthesized from $A_2$ and $B_4$ type monomers through Wittig polycondensation. The synthesized p-HPPV and m-HPPV were completely soluble in common organic solvents such as chloroform, tetrahydrofuran, 1,2-dichloroethane, etc. and thermal gravimetric analyses showed that p-HPPV and m-HPPV are stable up to $350^{\circ}C$. The molecular weights (from GPC), UV-visible, and photoluminescence maximum peaks of p-HPPV and m-HPPV are characterized in detail. The fabricated EL devices using the synthesized hyperbranched polymers, (ITO/(p-HPPV or m-HPPV)/Al), showed EL emission at about 507 nm and 481 nm (681 nm), respectively. Especially, EL device from m-HPPV were found to exhibit nearly white emission with approximate CIE coordinates of (0.31, 0.34) compared with (0.310, 0.316) of NTSC white color at $100\;cd/m^2$. The good photophysical properties combine with good film-form ability could make these hyperbranched polymers to be a potential candidate for the EL materials.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.10
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• pp.837-843
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• 2009

$TiO_2$(2 wt.%)-doped ZnO(TZO) films with thickness from 100 nm to 500 nm were prepared on polyethylene naphthalate(PEN) substrate under various rf-power range from 40 W to 80 W. Their electrical and optical properties were investigated as a function of rf-power. We think that these properties were closely related with the crystallization and the film density of TZO films. It was also presumed that the vaporization of the water vapor and other adsorbed particles such as an organic solvents can affect the electrical properties of the conventional transparent conductive oxide(TCO) films. On the other hand, since the TZO film deposited on glass substrate at room temperature with rf-power of 80 W shows a very low resistivity of $7.5\times10^{-4}\;\Omega{\cdot}cm$ and a very excellent transmittance over an average 85% in the visible range, that is comparable to that of ITO films. Therefore, we expect that the TZO films can be used as transparent electrode for optoelectronic devices such as touch-panels, flat-panel displays, and thin-film solar cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.6
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• pp.476-483
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• 2009

Cosmic ray is composed of nuclear particles moving at a light speed. The cosmic ray affects the performance and the reliability of semiconductor devices by ionizing the semiconductor material. In this study, the radiation effects of protons, electrons, and photons, which compose the cosmic ray, on the GOS(Geostationary Orbit Satellite) were evaluated using the Monte-Carlo N-Particle code. The GOS was chosen due to the comparatively long exposure to the cosmic ray as it stays in the geostationary orbit more than 10 years. As the absorbed dose of semiconductor from electrons is much larger than those of protons, photons, and the secondary radiation, most of the radiation exposure of the semiconductors in the GOS results from that of electrons. When we compare the calculated absorbed dose with the radio-resistance of semiconductor, the Intel 486 of the Intel company is not suitable for the GOS applications due to its low radio-resistance. However RH3000-20 of MIPS and Motorola 602/603e can be applied to the Satellite when the aluminium shield is thicker than 3 mm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.6
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• pp.466-468
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• 2009

The metal-insulator-silicon (MIS) capacitors with $SiO_2$ and high-k dielectrics ($HfO_2$, $Al_2O_3$) were fabricated, and the current-voltage characteristics were investigated. Especially, an effective barrier height between metal gate and dielectric was extracted by using Fowler-Nordheim (FN) plot and Direct Tunneling (DT) plot of quantum mechanical(QM) modeling. The calculated barrier heights of thermal $SiO_2$, ALD $SiO_2$, $HfO_2$ and $Al_2O_3$ are 3.35 eV, 0.6 eV, 1.75 eV, and 2.65 eV, respectively. Therefore, the performance of non-volatile memory devices can be improved by using engineered tunnel barrier which is considered effective barrier height of high-k materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.78-78
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• 2007

In semiconductor devices, Cu has been used for the formation of multilevel metal interconnects by the damascene technique. Also lower dielectric constant materials is needed for the below 65 nm technology node. However, the low-k materials has porous structure and they can be easily damaged by high down pressure during conventional CMP. Also, Cu surface are vulnerable to have surface scratches by abrasive particles in CMP slurry. In order to overcome these technical difficulties in CMP, electro-chemical mechanical planarization (ECMP) has been introduced. ECMP uses abrasive free electrolyte, soft pad and low down-force. Especially, electrolyte is an important process factor in ECMP. The purpose of this study was to characterize KOH and $KNO_3$ based electrolytes on electro-chemical mechanical. planarization. Also, the effect of additives such as an organic acid and oxidizer on ECMP behavior was investigated. The removal rate and static etch rate were measured to evaluate the effect of electro chemical reaction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.130-131
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• 2007

In this study, polyvinylidene fluoride/trifluoroethylene (PVDF-TrFE) was investigated. For a metal-ferroelectic-metal (MFM) structure, We obtained that the 70 nm-thick film showed the maximum polarization of $8.24\;{\mu}C/cm^2$, 2Pr of $6\;{\mu}C/cm^2$ and the coercive voltage of ${\pm}3.1\;V$ at 12 V. The 140 nm-thick film showed higher performance. However, the thicker film required a higher voltage. The current density was $10^{-6}{\sim}10^{-7}\;A/cm^2$ under 15 V. We can expect from these results that the electrical properties of the devices particularly ferroelectric thin film transistor using PVDF-TrFE copolymer, be able to be on the trade-off relationship between the remanent polarization and the leakage current.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.373-374
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• 2007

We have fabricated polymer light-emitting diodes(PLED) in a structure of Glass/ITO/PVK/Al. Poly(N-vinylcabazole) (PVK) was deposited on the ITO glass with the spin coating method. PVK thickness is respectively 500nm, 300nm, 250nm and 200nm with the spin coter rotation speed of 2000, 3000, 4000 and 5000rpm. V-I, wavelength-transmittance, P-L and SEM of the fabricated devices were measured. From the result of P-L measurement, it was kept the optic properties of PVK raw powder when PVK thickness is 250nm. The knee-voltage of PVK PLED with 250nm thickness was 7V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.174-175
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• 2007

A programmable metallization cell (PMC) memory structure with copper-saturated GeTe solid electrolyte films doped by nitrogen was prepared on a TiW bottom electrode by a co-sputtering technique at room temperature. The $Ge_{45}Te_{55}$ solid electrolyte films deposited with various $N_2$/Ar flow ratios showed an increase of crystallization temperature and especially, the electrolyte films deposited at $N_2$/Ar ratios above 30% showed a crystallization temperature above $400^{\circ}C$, resulting in surviving in a back-end process in semiconductor memory devices. The device with a 200 nm thick $Cu_{1-x}(Ge_{45}Te_{55})_x$ electrolyte switches at 1 V from an "off " state resistance, $R_{off}$, close to $10^5$ to an "on" resistance state, Ron, more than 20rders of magnitude lower for this programming current.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.439-440
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• 2007

To enhance the electron injection from the cathode of organic light-emitting diodes (OLEDs), We have studied characteristics of device that electron injection layer(EIL) is inserted between emissive layer and cathode. We fabricated bi-layer cathode $Li_2O$(x nm)/Al(100nm) and LiF(x nm)/Al(100nm) using LiF and $Li_2O$ as an electron injection layer. We analyzed the current efficiency, luminance efficiency, and external quantum efficiency of the device by varying the thickness of $Li_2O$ and LiF to be 0.5nm, 1nm, or 3nm. Using the EIL, we have obtained the efficiency of 7cd/A and the luminance of $20,000cd/m^2$. There is an improvement of efficiency by more than 3 times than the device without the $Li_2O$ layer.