• 한국전자파학회논문지
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• 제11권5호
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• pp.796-805
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• 2000

30dB의 선형이득과 2.6dB의 잡음지수 성능을 갖는 위성통신중계기용 30GHz대 저잡음증폭기 모듈이 MMIC와 박막 MIC기술로 개발되었다. 두 종의 MMIC 회로가 저잡음증폭기 모듈에 사용되었는데, 하나는 초저잡음용 MMIC 회로이고, 다른 하나는 광대역 고이득용 MMIC 회로이다. MMIC 회로 제작에 사용된 증폭소자는 0.15$mu extrm{m}$게이트 길이를 갖는 pHEMT이다. 두 개의 MMIC 회로를 상호 연결하고 저잡음증폭기 모듈을 완성하기 위하여 박막기술을 이용하여 마이크로스트립 선로를 구현하였으며, 안정된 DC 전원 공급을 위하여 후막기술을 이용한 바이어스 회로를 개발하였다. 저잡음증폭기 모듈의 입력측은 위성중계기의 안테나로부터의 신호를 받아들이기 위하여 도파관 형태로 설계되었으며, 출력측은 주파수변환부와의 접속을 위하여 K-컨넥터로 구현되었다. 모든 제작 공정에는 실제 위성용 부품 제작 기술이 도입되었으며, 위성중계기에 탑재되는 부품에 요구되는 온도시험 및 진동시험을 실시하였다. 제작된 저잡음증폭기 모듈은 동작목표 대역인 30~31GHz에서 30dB 이상의 이득, $\pm$0.3dB의 이득평탄도, 그리고 2.6dB이하의 우수한 잡음지수를 가진 것으로 측정되었다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.3.1-3.1
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• 2010

Water splitting reaction using photocatalysts is of great interest in the utilization of solar energy [1]. In the present work, visible light-responsive $TiO_2$ thin films (Vis-$TiO_2$) were prepared by a radio frequency magnetron sputtering (RF-MS) deposition method and applied for the separate evolution of $H_2$ and $O_2$ from water as well as the photofuel cell. Special attentions will be focused on the effect of HF treatment of Vis-$TiO_2$ thin films on their photocatalytic activities. Vis-$TiO_2$ thin films were prepared by an RF-MS method using a calcined $TiO_2$ plate and Ar as the sputtering gas. The Vis-$TiO_2$ thin films were then deposited on the Ti foil substrate with the substrate temperature at 873 K (Vis-$TiO_2$/Ti). Vis-$TiO_2$/Ti thin films were immersed in a 0.045 vol% HF solution at room temperature. The effect of HF treatments on the activity of Vis-$TiO_2$/Ti thin films for the photocatalytic water splitting reaction have been investigated. Vis-$TiO_2$/Ti thin films treated with HF solution (HF-Vis-$TiO_2$/Ti) exhibited remarkable enhancement in the photocatalytic activity for $H_2$ evolution from a methanol aqueous solution as well as in the photoelectrochemical performance under visible light irradiation as compared with the untreated Vis-$TiO_2$/Ti thin films. Moreover, Pt-loaded HF-Vis-$TiO_2$/Ti thin films act as efficient and stable photocatalysts for the separate evolution of $H_2$ and $O_2$ from water under visible light irradiation in the presence of chemical bias. Thus, HF treatment was found to be an effective way to improve the photocatalytic activity of Vis-$TiO_2$/Ti thin films. Furthermore, unique separate type photofuel cell was fabricated using a Vis-$TiO_2$ thin film as an electrode, which can generate electrical power under solar light irradiation by using various kinds of biomass derivatives as fuel. It was found that the introduction of an iodine ($I^-/{I_3}^-$) redox solution at the cathode side enables the development of a highly efficient photofuel cell which can utilize a cost-efficient carbon electrode as an alternative to the Pt cathode.

• 대한전자공학회논문지
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• 제16권4호
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• pp.36-46
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• 1979

본 연구에서는 N -채널 실리콘 게이트 제작기술에 의하여 일련의 크기를 가지는 커페시터와 트렌지스터들이 제작되었다. 그 결과 다양한 이온 주입 조걸, 즉 B 의 경우 에너지 30keV∼60keV와 도오스 3 × 10 ~ 5 × 10 개/㎠ 그리고 P 의 경우 에너지 1001keV∼ 175keV와 4 ×10 ~ 7×11개/㎠ 도오스 영역에서 이들에 대한 D.C. 인자들의 측정치들이 이론적인 계산치들과 비상, 분석되어 있다. 이 D.C. 인자들에는 threshold전압, 공핍층의 폭, 게이트 산화물 두께, 표면상태, 가동 하전입자 밀도, 전자의 이동도 그리고 마지막으로 누설전류가 있는데, 이중 실제 MOS의 제작에 있어서 특허 중요한 threshold전압에 있어서는, 커어브트레이서와 C - V plot을 통하여 측정된 값들이 실제 재산에서 이용된 SUPREM II 컴퓨우터 프로그램에 의한 결과와 훌륭히 접근하고 있다. 그 밖에 여기나온 D.C.인자들 중에서 도오핑 수준은 기판의 역 게이트 바이어스에서 threshold전압들로 부터 계산된 것이고, 역전도는 정의된 subthreshold 기울기로 부터 추산된 것임을 밝혀 둔다. 마지막으로 이와같은 D. C. 시험 결과들을 종합적으로 평가해 볼 때 만들어진 커페시터와 트렌지스터들이 N -채널 MOS I. C. 기억소자용으로 적합함을 보여주고 있다.

• ETRI Journal
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• 제24권4호
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• pp.290-298
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• 2002

We present, for the first time, a prototype active-matrix field emission display (AMFED) in which an amorphous silicon thin-film transistor (a-Si TFT) and a molybdenum-tip field emitter array (Mo-tip FEA) were monolithically integrated on a glass substrate for a novel active-matrix cathode (AMC) plate. The fabricated AMFED showed good display images with a low-voltage scan and data signals irrespective of a high voltage for field emissions. We introduced a light shield layer of metal into our AMC to reduce the photo leakage and back channel currents of the a-Si TFT. We designed the light shield to act as a focusing grid to focus emitted electron beams from the AMC onto the corresponding anode pixel. The thin film depositions in the a-Si TFTs were performed at a high temperature of above 360°C to guarantee the vacuum packaging of the AMC and anode plates. We also developed a novel wet etching process for $n^+-doped$ a-Si etching with high etch selectivity to intrinsic a-Si and used it in the fabrication of an inverted stagger TFT with a very thin active layer. The developed a-Si TFTs performed well enough to be used as control devices for AMCs. The gate bias of the a-Si TFTs well controlled the field emission currents of the AMC plates. The AMFED with these AMC plates showed low-voltage matrix addressing, good stability and reliability of field emission, and good light emissions from the anode plate with phosphors.

• 한국전자파학회논문지
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• 제17권9호
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• pp.860-865
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• 2006

본 논문에서는 가변형 $Bi_2O_3-ZnO-Nb_2O_5(BZN)$ Pyrochlore 박막을 이용한 고가변형 inter-digital capacitor를 제안하였다. 가장자리 전계 효과를 이용한 가변성의 향상과 DC 전압의 감소를 위해 inter-digital capacitor의 전극이 박막 내부에 삽입되었다. 2.5D simulator를 이용한 설계 결과, 제 안된 구조의 inter-digital capacitor(IDC)가 일반적인 구조의 IDC에 비해 가변성이 10 % 향상되었다. 제안된 IDC는 설계 결과를 바탕으로 실리콘 기판 위에 BZN 박막을 이용하여 제작되었다. BZN 박막은 reactive RF magnetron sputtering 방법을 이용하여 증착되었다. 제작된 inter-digital capacitor는 5.8 GHz와 18 V의 DC 인가 전압에서 최대 가변율이 50 %였다.

• 한국재료학회지
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• 제20권11호
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• pp.570-574
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• 2010

A diamond-like carbon (DLC) film deposited on a WC disk was investigated to improve disk wear resistance for injection molding of zirconia optical ferrule. The deposition of DLC films was performed using the filtered vacuum arc ion plating (FV-AIP) system with a graphite target. The coating processing was controlled with different deposition times and the other conditions for coating, such as input power, working pressure, substrate temperature, gas flow, and bias voltage, were fixed. The coating layers of DLC were characterized using FE-SEM, AFM, and Raman spectrometry; the mechanical properties were investigated with a scratch tester and a nano-indenter. The friction coefficient of the DLC coated on the WC was obtained using a pin-on-disk, according to the ASTM G163-99. The thickness of DLC films coated for 20 min. and 60 min. was about 750 nm and 300 nm, respectively. The surface roughness of DLC films coated for 60 min. was 5.9 nm. The Raman spectrum revealed that the G peak of DLC film was composed of $sp^3$ amorphous carbon bonds. The critical load (Lc) of DLC film obtained with the scratch tester was 14.6 N. The hardness and elastic modulus of DLC measured with the nano-indenter were 36.9 GPa and 585.5 GPa, respectively. The friction coefficient of DLC coated on WC decreased from 0.2 to 0.01. The wear property of DLC coated on WC was enhanced by a factor of 20.

• 한국항해항만학회지
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• 제27권5호
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• pp.505-511
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• 2003

본 논문에서는 UHF(470∼806 MHz) 대역에서 전송장치로 사용 가능한 DTV 중계기용 1 Watt 급 구동증폭단을 설계 및 제작하였다. 구동증폭단은 유전율 2.53, 두께 0.8 mm 기판을 사용하여, 전치증폭기 및 1 Watt 단위증폭기를 단일기판상에 집적화 하였다. 바이어스 전압 28 V DC, 전류 900 mA를 구동증폭단에 인가하였을 때, 470∼806 MHz의 대역에서 53.5 dB 이상의 이득, $\pm$0.5 dB의 이득 평탄도 및 -12 dB 이하의 입ㆍ출력 반사손실이 나타났다. 또한 출력전력이 1 Watt일 때 사용주파수 대역에서 2 MHz 주파수 간격의 두 신호를 구동증폭단에 입력하여 설계사양보다 우수한 48 dBc 이상의 상호변조왜곡 특성이 나타남을 알 수 있었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2001년도 춘계학술발표회 초록집
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• pp.14-14
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• 2001

Nitride films such as TiN, CrN etc. deposited on glass by PVD processes have been developed for many industrial applications. These nitride films deposited on glass were widely used for not only decorative and optical coatings but also wear and corrosion resistance coatings employed as dies and molds made of glass for the example of lens forming molds. However, the major problem of nitride coatings on glass by PVD process is non-uniform film owing to pin-hole and micro crack. It is estimated that nonuniform coating is influenced by a different surface energy between metal nitrides and glass due to binding states. In this work, therefore, for the evaluation of nucleation and growth mechanism of nitride films on glass TiN and CrN film were synthesized on glass with various nitrogen partial pressure by unbalanced magnetron sputtering. Prior to deposition, for the examination of relationship between surface energy and film microstructure plasma pre-treatment process was carried out with various argon to hydrogen flow rate and substrate bias voltage, duty cycle and frequency by using pulsed DC power supply. Surface energy owing to the different plasma pre-treatment was calculated by the measurement of wetting angle and surface conditions of glass were investigated by X-ray Photoelectron Spectroscopy(XPS) and Atomic Force Microscope(AFM). The microstructure change of nitride films on glass with increase of film thickness were analyzed by X-Ray Diffraction(XRD) and Scanning Electron Microscopy(SEM).

• 한국결정성장학회지
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• 제21권4호
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• pp.153-157
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• 2011

Inductively Coupled Plasma(ICP)를 이용하여 다양한 조건으로 표면 처리한 Si(100) 기관 위에 Low Pressure Chemical Vapor Deposition(LPCVD)를 이용하여 Ge 층을 이종접합 성장하고, Ge 층 성장 초기의 표면 상태를 Scanning Electron Microscopy(SEM)을 통해 분석하였다. ICP를 이용하여 표면 처리된 Si(100) 기판 위에 성장된 Ge 층의 경우 ICP 처리하지 않은 시편보다 Ge 성장율이 약 5배 이상 증가되었다. ICP 처리된 시편의 Ge 성장률 증가는 ICP 표면 처리 공정으로 Si 기관 표면에서 떨어져 나간 missing dimer가 Ge adatom들에 핵을 형성할 자리를 제공하여 Ge island의 형성과 융합을 촉진시키는 것으로 사료된다.

• 한국수소및신에너지학회논문집
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• 제18권4호
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• pp.452-457
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• 2007

Titanium foil and mesh(anodized tubular $TiO_2$ electrode, ATTE) were anodized in a bath at $5^{\circ}C$ with 20V external bias applied, then annealed at different temperatures($450^{\circ}C{\sim}850^{\circ}C$) to obtain tubular $TiO_2$ on the Ti substrate. The prepared sample was used to investigate rate of hydrogen production as well as Cr(VI) reduction. The ATTEs annealed at relatively lower temperatures showed higher activity than those at relatively higher temperatures. In particular, the Cr(VI) reduction was pH-dependent. To improve photocatalytic Cr(VI) reduction with the ATTEs, two configurations, fixing foil type and rotating mesh type, were also compared. As a result, the rotating mesh type was much more effective for Cr(VI) reaction than the former due to the more efficient use of the light. In the rotating type reactor, as the rotating speed increased, the rate of the Cr(VI) reduction was getting faster.