• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.374-376
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• 2009

In this paper, a CPW fed and inversed U-type monopole structure wide slot antenna for novel broadband calacturictics is proposed. To enhance the impedance bandwidth of the wide slot antenna, we proposed the wide slot structure with cpw-fed which is combined with four $\lambda/2$ rectangular radiation modified monopole and inductively coupled. The measured impedance bandwidth is about 2.3 GHz(3.85~6.15 GHz) at 10 dB and the simulated antenna gain is about 6 dBi at 5.4 GHz.

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.54-54
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• 2005

• Journal of the Korean institute of surface engineering
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• v.41 no.6
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• pp.279-286
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• 2008

Numerical analysis is done to investigate which would be the most influencing process parameter in determining the uniformity of deposition thickness in TiN ICP-CVD(inductively coupled plasma chemical vapor deposition). Two configurations of ICP antenna are modeled; side and top planar. Side and top gas inlets are considered with each ICP antenna geometries. Precursor for TiN deposition was TDMAT(Tetrakis Diethyl Methyl Amido Titanium). Two step volume dissociation of TDMAT is used and absorption, desorption and deposition surface reactions are included. Most influencing factors are H and N concentration dissociated by electron impact collisions in plasma volume which depends on the relative positions of gas inlet and ICP antenna generated hot plasma region. Low surface recombination of N shows hollow type concentration, but H gives a bell type distribution. Film thickness at substrate edges is sensitive to gas flow rate and at high pressures getting more dependent on flow characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.39-42
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• 2000

The effect of excess Pb contents on the etching of PZT thin films and their electrical properties has been investigated. Ferroelectric PZT(53/47) thin films were prepared by the metal alkoxide-based Sol-Gel method, in which they were spin-coating on P7Ti/Si02/Si substrate using the PZT(53/47) stock solutions with various excess Pb contents. Etching of PZT film was performed using planar inductively coupled Ar/Cl$_2$/BCl$_3$ plasma. The etch rate of PZT film was 2450 $\AA$/min at Ar(20)/BCl$_3$(80) gas mixing ratio and substrate temperature of 8$0^{\circ}C$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.6 s.121
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• pp.648-655
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• 2007

In this paper, we introduce a dual coil antenna which is useful for reducing the effects of radio frequency noise in an RFID system. A dual coil antenna is composed of two identical coils that are connected in series. The noise voltages in the two coils almost disappear when they are added because the magnitudes are equal and the polarities are opposite. The noise in an RFID reader with a dual coil antenna was 15 dB lower than that with a single coil antenna.

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.73-73
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• 2005

• Journal of the Optical Society of Korea
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• v.18 no.3
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• pp.283-287
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• 2014

Square lattice nano-hole arrays with diameters and periodicities of 200 and 500 nm, respectively, are fabricated on InGaN/GaN blue light emitting diodes (LEDs) using electron-beam lithography and inductively coupled plasma reactive ion etching processes. Cathodoluminescence (CL) investigations show that light emission intensity from the LEDs with the nano-hole arrays is enhanced compared to that from the planar sample. The CL intensity enhancement factor decreases when the nano-holes penetrate into the multiple quantum wells (MQWs) due to the plasma-induced damage and the residues. Wet chemical treatment using KOH solution is found to be an effective method for light extraction from the nano-patterned LEDs, especially, when the nano-holes penetrate into the MQWs. About 4-fold CL intensity enhancement factor is achieved by the KOH treatments after the dry etching for the sample with a 250-nm deep nano-hole array.

• Korean Journal of Materials Research
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• v.15 no.3
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• pp.161-165
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• 2005

We investigated selective dry etching of GaAs over AlGaAs and InGaP in high density planar inductively coupled $BCl_3/SF_6$ plasmas. The process parameters were ICP source power (0-500 W), RE chuck power (0-30W) and gas composition $(60-100\%\;BCl_3\;in\;BCl_3/SF_6)$. The process results were characterized in terms of etch rate, selectivities of GaAs over AlGaAs and InGaP, surface morphology, surface roughness and residues after etching. $BCl_3/SF_6$ selective etching of GaAs showed quite good results in this study. Selectivities of GaAs $(GaAs:AlGaAs\~36:1,\;GaAs:InGaP\~45:1)$ were superior at $18BCl_3/2SF_6$, 20 W RF chuck power, 300 W ICP source power and 7.5 mTorr. Addition of $(5-15\%)SF_6\;to\;BCl_3$ produced relatively high selectivities of GaAs over AlGaAs and InGaP during etching due to decrease of etch rates of AlGaAs and InGaP (boiling points of etch products: $AlF_3\~1300^{\circ}C,\;InF_3>1200^{\circ}C$ at atmosphere) at the condition. SEM and AFM data showed slightly sloped sidewall and somewhat rough surface$(RMS\~9nm)$. XPS study on the surface of processed GaAs proved a very clean surface after dry etching. It shows that planar inductively coupled $BCl_3/SF_6$ plasmas could be a good candidate for selective dry etching of GaAs over AlGaAs and InGaP.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.63-63
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• 2003

플라즈마 공정은 DRAM, 이종접합 양극성 트랜지스터(HBTs), 레이저, 평면도파로(planar lightwave circuit)와 같은 전자소자 및 광조자 제작에 있어서 핵심 공정중의 하나이다. 최근 미세 구조의 크기가 극도로 감소하게 됨에 따라 실제 소작 제작에 있어서 미세한 모양을 식각하는 공정이 매우 중요하게 되었다. 그 중에서 고밀도 유도결합 플라즈마(high density inductively coupled plasma)를 이용한 기술은 빠르고 정확한 식각률, 우수한 식각 균일도와 높은 재현성 때문에 습식식각 기술보다 선호되고 있다. 본 연구는 평판형(planar) 고밀도 유도결합 플라즈마 식각장치를 이용하여 BCl$_3$와 BCl$_3$/Ar 플라즈마에 따른 AlGaAs/GaAs의 식각결과를 비교 분석하였다. 공정 변수는 ICP 소스(source power)파워, RIE 척(chuck) 파워, 공정 압력, 그리고 Ar 조성비(0-100%)이었다. BCl$_3$에 Ar을 첨가하게 되면 순수한 BCl$_3$ 플라즈마에서의 AlGaAs/GaAs 식각률(> 3000 $\AA$/min) 보다 분당 약 1000$\AA$ 이상 높은 식각률(>4000 $\AA$/min)을 나타내었다. 이 결과는 Ar 플라즈마의 이온보조(ion-assisted)가 식각률 증가에 기인한다고 예측된다. 그리고 전자주사 현미경(SEM)과 원자력간 현미경(AFM)을 사용하여 식각 후 표면 거칠기 및 수직 측벽도 둥을 분석하였다. 마지막으로 XPS를 이용하여 식각된 후에 표면에 남아 있는 잔류 성분 분석을 연구하였다. 본 결과를 종합하면 BCl$_3$에 기초한 평판형 유도결합 플라즈마는 AlGaAs/GaAs 구조의 식각시 많은 우수한 특성을 보여주었다.79$\ell/\textrm{cm}^3$, 0.016$\ell/\textrm{cm}^3$, 혼합재료 2는 0.045$\ell/\textrm{cm}^3$, 0.014$\ell/\textrm{cm}^3$, 혼합재료 3은 0.123$\ell/\textrm{cm}^3$, 0.017$\ell/\textrm{cm}^3$, 혼합재료 4는 0.055$\ell/\textrm{cm}^3$, 0.016$\ell/\textrm{cm}^3$, 혼합재료 5는 0.031$\ell/\textrm{cm}^3$, 0.015$\ell/\textrm{cm}^3$, 혼합재료 6은 0.111$\ell/\textrm{cm}^3$, 0.020$\ell/\textrm{cm}^3$로 나타났다. 3. 단일재료의 악취흡착성능 실험결과 암모니아는 코코넛, 소나무수피, 왕겨에서 흡착능력이 우수하게 나타났으며, 황화수소는 펄라이트, 왕겨, 소나무수피에서 다른 재료에 비하여 상대적으로 우수한 것으로 나타났으며, 혼합충진재는 암모니아의 경우 코코넛과 펄라이트의 비율이 70%:30%인 혼합재료 3번과 소나무수피와 펄라이트의 비율이 70%:30%인 혼합재료 6번에서 다른 혼합재료에 비하여 우수한 것으로 나타났으며, 황화수소의 경우 혼합재료에 따라 약간의 차이를 보였다. 4. 코코넛과 소나무수피의 경우 암모니아가스에 대한 흡착성능은 거의 비슷한 것으로 사료되며, 코코넛의 경우 전량을 수입에 의존하고 있다는 점에서 국내 조달이 용이하며, 구입 비용도 적게 소요되는 소나무수피를 사용하는 것이 경제적이라고 사료된다. 5. 마지막으로 악취제거 미생물균주를 접종한 소나무수피 70%와 펄라이트 30%의 혼합재료를 24시간동안 장기간 운전

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.427-427
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• 2016

Organic-inorganic hybrid perovskite have attracted significant attention as a new revolutionary light absorber for photovoltaic device due to its remarkable characteristics such as long charge diffusion lengths (100-1000nm), low recombination rate, and high extinction coefficient. Recently, power conversion efficiency of perovskite solar cell is above 20% that is approached to crystalline silicon solar cells. Planar heterojunction perovskite solar cells have simple device structure and can be fabricated low temperature process due to absence of mesoporous scaffold that should be annealed over 500 oC. However, in the planar structure, controlling perovskite film qualities such as crystallinity and coverage is important for high performances. Those controlling methods in one-step deposition have been reported such as adding additive, solvent-engineering, using anti-solvent, for pin-hole free perovskite layer to reduce shunting paths connecting between electron transport layer and hole transport layer. Here, we studied the effect of alkali metal halide to control the fabrication process of perovskite film. During the morphology determination step, alkali metal halides can affect film morphologies by intercalating with PbI2 layer and reducing $CH3NH3PbI3{\cdot}DMF$ intermediate phase resulting in needle shape morphology. As types of alkali metal ions, the diverse grain sizes of film were observed due to different crystallization rate depending on the size of alkali metal ions. The pin-hole free perovskite film was obtained with this method, and the resulting perovskite solar cells showed higher performance as > 10% of power conversion efficiency in large size perovskite solar cell as $5{\times}5cm$. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma optical emission spectrometry (ICP-OES) are analyzed to prove the mechanism of perovskite film formation with alkali metal halides.