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BCl<sub>3</sub> 기반의 혼합가스들을 이용한 InP 고밀도 유도결합 플라즈마 식각
조관식,임완태,백인규,이제원,전민현,Cho, Guan-Sik,Lim, Wan-tae,Baek, In-Kyoo,Lee, Je-won,Jeon, Min-hyun 한국재료학회 2003 한국재료학회지 Vol.13 No.12
We studied InP etching in high density planar inductively coupled $BCl_3$and $BCl_3$/Ar plasmas(PICP). The investigated process parameters were PICP source power, RIE chuck power, chamber pressure and $BCl_3$/Ar gas composition. It was found that increase of PICP source power and RIE chuck power increased etch rate of InP, while that of chamber pressure decreased etch rate. Etched InP surface was clean and smooth (RMS roughness <2 nm) with a moderate etch rate (300-500 $\AA$/min) after the planar $BCl_3$/Ar ICP etching. It may make it possible to open a new regime of InP etching with $CH_4$$H_2$-free plasma chemistry. Some amount of Ar addition (<50%) also improved etch rates of InP, while too much Ar addition reduced etch rates of InP.
반응성 이온 식각법에 의해 제작된 탄소나노튜브 전극의 전기화학적 특성
황숙현,최현광,김상효,한영문,전민현,Hwang, Sook-Hyun,Choi, Hyon-Kwang,Kim, Sang-Hyo,Han, Young-Moon,Jeon, Min-Hyon 한국재료학회 2011 한국재료학회지 Vol.21 No.2
In this work, fabrication and electrochemical analysis of an individual multi-walled carbon nanotube (MWNT) electrode are carried out to confirm the applicability of electrochemical sensing. The reactive ion etching (RIE) process is performed to obtain sensitive MWNT electrodes. In order to characterize the electrochemical properties, an individual MWNT is cut by RIE under oxygen atmosphere into two segments with a small gap: one segment is applied to the working electrode and the other is used as a counter electrode. Electrical contacts are provided by nanolithography to the two MWNT electrodes. Dopamine is specially selected as an analytical molecule for electrochemical detection using the MWNT electrode. Using a quasi-Ag/AgCl reference electrode, which was fabricated by us, the nanoelectrodes are subjected to cyclic voltammetry inside a $2{\mu}L$ droplet of dopamine solution. In the experiment, RIE power is found to be a more effective parameter to cut an individual MWNT and to generate "broken" open state, which shows good electrochemical performance, at the end of the MWNT segments. It is found that the pico-molar level concentration of analytical molecules can be determined by an MWNT electrode. We believe that the MWNT electrode fabricated and treated by RIE has the potential for use in high-sensitivity electrochemical measurement and that the proposed scheme can contribute to device miniaturization.
레이더에서 고고도 표적물의 고도 예측 성능 향상을 위한 한국형 지수 모델 개발에 관한 연구
문현욱(Hyunwook Moon),전민현(Min-Hyun Jeon),김우중(WooJoong Kim),오성근(Seong Keun Oh),이종현(Jong Hyun Lee),권세웅(Sewoong Kwon),윤영중(Young Joong Yoon) 한국전자파학회 2012 한국전자파학회논문지 Vol.23 No.7
본 논문에서는 레이더 이용 시 대기 굴절에 의한 고고도 표적물의 고도 오차를 최소화하기 위한 한국형 지수모델을 제안하였다. 이를 위해 한국 7개 기상 관측소에서 6년간 측정된 데이터를 바탕으로 표면 굴절도(surface refractivity)와 굴절도 감쇄율(refractivity gradient) 간의 상관 관계를 최소 자승법을 이용하여 도출하고, 이를 지수모델에 적용하였다. 또한, 제안된 모델의 검증을 위해 표준 대기(standard atmosphere) 모델, CRPL(Central Radio Propagation Lab.) 지수 모델, 제안된 한국형 지수 모델에 대한 고도 오차를 광선 추적법을 이용하여 도출하고, 그 특성을 분석하였다. 그 결과, 표준 대기 모델에 비해서는 50~60 %, CRPL 지수 모델에 비해서는 약 60 % 수준의 고도 오차를 나타내 제안된 모델을 적용 시 레이더의 고도 예측 성능을 향상시킬 수 있음을 확인하였다. In this paper, an exponential model of Korea is proposed to minimize an altitude-error of high-altitude target due to atmosphere refraction at radar system. The relation between surface refractivity and refractivity gradient, which is extracted using the least square fit from the measured data at 7 weather stations, is applied to the exponential model. And in order to verify the proposed model, the altitude-errors for a standard atmosphere, a CRPL(Central Radio Propagation Lab.) exponential model, the proposed model are extracted and analyzed using a ray tracing. As a result, the proposed model can improve the altitude estimation performance of radar compared to conventional atmosphere refractive index models.
전훈하,노경석,김도현,최원봉,전민현,Jeon, Hoon-Ha,Verma, Ved Prakash,Noh, Kyoung-Seok,Kim, Do-Hyun,Choi, Won-Bong,Jeon, Min-Hyon 한국진공학회 2007 Applied Science and Convergence Technology Vol.16 No.5
본 논문에서는 zinc oxide (ZnO)와 gallium이 도핑 된 zinc oxide (GZO)를 이용하여 radio frequency (RF) magnetron sputtering 방법에 의해 상온에서 제작된 bottom-gate 박막 트랜지스터의 특성을 평가하고 분석하였다. 게이트 절연층 물질로서 새로운 물질을 사용하지 않고 열적 성장된 $SiO_2$를 사용하여 게이트 누설 전류를 수 pA 수준까지 줄일 수 있었다. ZnO와 GZO 박막의 표면 제곱평균제곱근은 각각 1.07 nm, 1.65 nm로 측정되었다. 그리고 ZnO 박막은 80% 이상, GZO 박막은 75% 이상의 투과도를 가지고 있었고, 박막의 두께에 따라 투과도가 달라졌다. 또한 두 시료 모두 (002) 방위로 잘 정렬된 wurtzite 구조를 가지고 있었다. 제작된 ZnO 박막 트랜지스터는 2.5 V의 문턱 전압, $0.027\;cm^2/(V{\cdot}s)$의 전계효과 이동도, 104의 on/off ratio, 1.7 V/decade의 gate voltage swing 값들을 가지고 있었고, enhancement 모드 특성을 가지고 있었다. 반면에 GZO 박막 트랜지스터의 경우에는 -3.4 V의 문턱 전압, $0.023\;cm^2/(V{\cdot}s)$의 전계효과 이동도, $2{\times}10^4$의 on/off ratio, 3.3 V/decade의 gate voltage swing 값들을 가지고 있었고, depletion 모드 특성을 가지고 있었다. 우리는 기존의 ZnO와 1wt%의 Ga이 도핑된 ZnO를 이용하여 두 가지 모드의 트랜지스터 특성을 보이는 박막 트랜지스터를 성공적으로 제작하고 분석하였다. In this paper we present a bottom-gate type of zinc oxide (ZnO) and Gallium (Ga) doped zinc oxide (GZO) based thin film transistors (TFTs) through applying a radio frequency (RF) magnetron sputtering method at room temperature. The gate leakage current can be reduced up to several ph by applying $SiO_2$ thermally grown instead of using new gate oxide materials. The root mean square (RMS) values of the ZnO and GZO film surface were measured as 1.07 nm and 1.65 nm, respectively. Also, the transmittances of the ZnO and GZO film were more than 80% and 75%, respectively, and they were changed as their film thickness. The ZnO and GZO film had a wurtzite structure that was arranged well as a (002) orientation. The ZnO TFT had a threshold voltage of 2.5 V, a field effect mobility of $0.027\;cm^2/(V{\cdot}s)$, a on/off ratio of $10^4$, a gate voltage swing of 17 V/decade and it operated in a enhancement mode. In case of the GZO TFT, it operated in a depletion mode with a threshold voltage of -3.4 V, a field effect mobility of $0.023\;cm^2/(V{\cdot}s)$, a on/off ratio of $2{\times}10^4$ and a gate voltage swing of 3.3 V/decade. We successfully demonstrated that the TFTs with the enhancement and depletion mode type can be fabricated by using pure ZnO and 1wt% Ga-doped ZnO.
BCl<sub>3</sub>및 BCl<sub>3</sub>/Ar 고밀도 유도결합 플라즈마를 이용한 GaAs와 AlGaS 반도체 소자의 건식식각
임완태,백인규,이제원,조관식,전민현,Lim, Wan-tae,Baek, In-kyoo,Lee, Je-won,Cho, Guan-Sik,Jeon, Min-hyun 한국재료학회 2003 한국재료학회지 Vol.13 No.10
We investigated dry etching of GaAs and AiGaAs in a high density planar inductively coupled plasma system with BCl$_3$and BCl$_3$/Ar gas chemistry. A detailed etch process study of GaAs and ALGaAs was peformed as functions of ICP source power, RIE chuck power and mixing ratio of $BCl_3$ and Ar. Chamber process pressure was fixed at 7.5 mTorr in this study. The ICP source power and RIE chuck power were varied from 0 to 500 W and from 0 to 150 W, respectively. GaAs etch rate increased with the increase of ICP source power and RIE chuck power. It was also found that etch rates of GaAs in $15BCi_3$/5Ar plasmas were relatively high with applied RIE chuck power compared to pure 20 sccm $BCl_3$plasmas. The result was the same as AlGaAs. We expect that high ion-assisted effect in $BCl_3$/Ar plasma increased etch rates of both materials. The GaAs and AlGaAs features etched at 20 sccm $BCl_3$and $15BCl_3$/5Ar with 300 W ICP source power, 100 W RIE chuck power and 7.5 mTorr showed very smooth surfaces(RMS roughness < 2 nm) and excellent sidewall. XPS study on the surfaces of processed GaAs also proved extremely clean surfaces of the materials after dry etching.
실리콘 기판의 산화층이 다중벽 탄소나노튜브 성장에 미치는 영향
김금채,이수경,김상효,황숙현,전민현,Kim, Geum-Chae,Lee, Soo-Kyoung,Kim, Sang-Hyo,Hwang, Sook-Hyun,Choi, Hyon-Kwang,Jeon, Min-Hyon 한국재료학회 2009 한국재료학회지 Vol.19 No.1
Multi-walled carbon nanotubes (MWNTs) were synthesized on different substrates (bare Si and $SiO_2$/Si substrate) to investigate dye-sensitized solar cell (DSSC) applications as counter electrode materials. The synthesis of MWNTs samples used identical conditions of a Fe catalyst created by thermal chemical vapor deposition at $900^{\circ}C$. It was found that the diameter of the MWNTs on the Si substrate sample is approximately $5{\sim}10nm$ larger than that of a $SiO_2$/Si substrate sample. Moreover, MWNTs on a Si substrate sample were well-crystallized in terms of their Raman spectrum. In addition, the MWNTs on Si substrate sample show an enhanced redox reaction, as observed through a smaller interface resistance and faster reaction rates in the EIS spectrum. The results show that DSSCs with a MWNT counter electrode on a bare Si substrate sample demonstrate energy conversion efficiency in excess of 1.4 %.
IRFPA용 CMOS readout 회로를 위한 저잡음 OP-AMP
김소희(So Hee Kim),박민영(Min Young Park),최충기(Chung Ki Choi),강명훈(Myung Hoon Kang),문준희(Jun Hee Mun),박치영(Chi Young Park),박용수(Yong Soo Park),송한정(Han Jung Song),전민현(Min Hyun Jeon) 대한전자공학회 2006 대한전자공학회 학술대회 Vol.2006 No.11
A CMOS ROIC (ReadOut Integrated Circuit) for IRFPA (InfraRed Focal Plane Array) detector is a key component in uncooled thermal imaging systems. For a good IR (InfraRed) detector, low noise ROIC is needed. In this paper, a low noise CMOS OP-AMP for ROIC circuit of the 32×32 IR bolometer detector has been designed. HSPICE simulation results with a 0.35 ㎛ CMOS technology are unit gain bandwidth of 12.8 ㎒, 89 ㏈ open loop gain, 8 V/㎛ slew rate, 600 ㎱ settling time and 67° phase margin.
투명전극 응용을 위한 ZnO박막과 Ga 도핑 된 ZnO박막의 성장 후 열처리에 따른 특성분석
장재호,배효준,이지수,정광현,최현광,전민현,Jang, Jae-Ho,Bae, Hyo-Jun,Lee, Ji-Su,Jung, Kwang-Hyun,Choi, Hyon-Kwang,Jeon, Min-Hyon 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.7
Polycrystalline ZnO and Ga doped ZnO (GZO) films are deposited on glass substrate by RF magnetron sputtering at room temperature. The characteristics of ZnO and GZO films are investigated with X-ray diffraction measurement, UV-VIS-NIR spectrophotometer $(250{\sim}1200nm)$ and hall measurement. The post-growth thermal treatment of these films is carried out in N2 ambient at $500^{\circ}C$ for 30 min and an hour. ZnO and GZO films have different changing behavior of structural and optical properties by annealing. To use transparent conductive films for solar cell, films should have not only high transmittance but also good electrical property. Although as deposited GZO films have electrical properties than ZnO films, GZO films have not good transmittance properties. Consequently, we succeed that the high transmittance of GZO films is improved by annealing process.
염료감응형 태양전지의 탄소나노튜브 상대전극의 광투과도와 전기화학적 특성이 에너지 변환 효율에 미치는 영향
한영문,황숙현,강명훈,김영주,김현국,김상효,배효준,최현광,전민현,Han, Young-Moon,Hwang, Sook-Hyun,Kang, Myung-Hoon,Kim, Young-Joo,Kim, Hyun-Kook,Kim, Sang-Hyo,Bae, Hyo-Jun,Choi, Hyon-Kwang,Jeon, Min-Hyon 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.4
In this work, electrochemical characteristics and optical transmittance of carbon nanotubes (CNTs) counter electrodes which had different amount of CNTs in CNTs slurries were analyzed. Two-step heat treatment processes were applied to achieve well-fabricated CNTs electrode. Three sets of CNTs electrodes and dye-sensitized solar cells (DSSCs) with CNTs counter electrodes were prepared. As the amount of CNTs increased, sheet resistance of CNTs electrode decreased. CNTs electrode with low sheet resistance had low electrochemical impedance and fast redox reaction. On the other hand, in case of CNTs counter electrode with low density of CNTs, performance of the dye-sensitized solar cell was improved due to its high optical transmittance. We found that the transmittance of CNTs counter electrode influence the performance of dye-sensitized solar cells.
0.35㎛ CMOS 공정을 이용한 Integrate and Fire Neuron model 구현
김진수(Jin Su Kim),이효연(Hyo Yeon Lee),정진우(Jin Woo Jung),김소희(So Hee Kim),강명훈(Myung Hoon Kang),김남태(Nam Tae Kim),송한정(Han Jung Song),전민현(Min Hyun Jeon) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.7
A new integrate and fire neuron with a synapse function for biological neuron modelling has been designed in a 0.35 ㎛ double poly CMOS process This neuron model generate a voltage output signal with a current input pulse. It consists of several MOS transistors and capacitors. SPICE simulation results are presented for the proposed I&F neuron and I&F series chain with synapses.