• 한국결정성장학회지
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• 제11권1호
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• pp.20-26
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• 2001

Ti와 B을 각각의 증발원으로 한 2원 전자빔 증착법으로 500$^{\circ}$의 기판온도에서 (100) Si 기판 위에 티타늄 붕화물 (${TiB}_{x}$) 박막을 증착시켰다. 이 방법은 여러 가지 boron-to-totanium ratio ($0{\le}B/Ti \le 2.5$)를 가지는 비당량 (${TiB}_{x}$ 박막의 표면 조도 역시 B/Ti비에 의존하여 변화되었다. 그리고 Pure Ti 박막은 (002)면의 우선 성장거동을 나타내었으나, $B/Ti{\ge}1.0$의 경우 (111)면의 우선 성장거동을 보이는 단일상의 TiB 박막이 성장되었다. 그러나 B농도가 더욱 증가됨에 따라 육방정계의 ${TiB}_{2}$상이 형성되기 시작하여 $B/Ti{\ge}2.0$ 의 조성비를 가지는 박막에서는 단일상의 ${TiB}_{2}$ 화합물을 나타내었다. 그리고 Si 기판상에 증착된 ${TiB}_{x}$ 박막의 잔류응력은 B/Ti비에 의존하나, 2원 전자빔 증착법으로 성장된 모든 박막에서 3~$20{\times}^9$dyn/$\textrm{cm}^2$ 정도의 인장응력을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.11-11
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• 2010

Thin-film-transistors (TFTs) that can be deposited at low temperature have recently attracted lots of applications such as sensors, solar cell and displays, because of the great flexible electronics and transparent. Transparent and flexible transistors are being required that high mobility and large-area uniformity at low temperature [1]. But, unfortunately most of TFT structures are used to be $SiO_2$ as gate dielectric layer. The $SiO_2$ has disadvantaged that it is required to high driving voltage to achieve the same operating efficiency compared with other high-k materials and its thickness is thicker than high-k materials [2]. To solve this problem, we find lots of high-k materials as $HfO_2$, $ZrO_2$, $SiN_x$, $TiO_2$, $Al_2O_3$. Among the High-k materials, $Al_2O_3$ is one of the outstanding materials due to its properties are high dielectric constant ( ~9 ), relatively low leakage current, wide bandgap ( 8.7 eV ) and good device stability. For the realization of flexible displays, all processes should be performed at very low temperatures, but low temperature $Al_2O_3$ grown by sputtering showed deteriorated electrical performance. Further decrease in growth temperature induces a high density of charge traps in the gate oxide/channel. This study investigated the effect of growth temperatures of ALD grown $Al_2O_3$ layers on the TFT device performance. The ALD deposition showed high conformal and defect-free dielectric layers at low temperature compared with other deposition equipments [2]. After ITO was wet-chemically etched with HCl : $HNO_3$ = 3:1, $Al_2O_3$ layer was deposited by ALD at various growth temperatures or lift-off process. Amorphous InGaZnO channel layers were deposited by rf magnetron sputtering at a working pressure of 3 mTorr and $O_2$/Ar (1/29 sccm). The electrodes were formed with electron-beam evaporated Ti (30 nm) and Au (70 nm) bilayer. The TFT devices were heat-treated in a furnace at $300^{\circ}C$ and nitrogen atmosphere for 1 hour by rapid thermal treatment. The electrical properties of the oxide TFTs were measured using semiconductor parameter analyzer (4145B), and LCR meter.

• 한국재료학회지
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• 제6권7호
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• pp.723-732
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• 1996

ICB 공정으로 선행 증착한 Cu Seeding 층이 이후의 CVD 공정으로 증착하는 최종의 Cu 박막의 기계적 전기적 특성에 미치는 영향을 고찰하였고, seening을 하지 않은 CVD-Cu 박막과의 특성을 비교하였다. seeding 층을 형성한 경우의 CVD-Cu 박막에 있어서 증착 속도가 증가하였으며, grain 크기의 균일성도 향상되는 경향을 보였다. 증착된 Cu 박막은 seening에 무관하게 모두 FCC 우선배향인 (111)의 결정배향을 나타냈으며, seeding 우에 성정된 박막의 경우 $I_{111}/I_{200}$비가 향상되었다.$ 180^{\circ}C$의 동일 조건하에서 증착하는 경우 $40\AA$ seeding층 위에 성장한 박막의 전기비저항이 $2.42\mu$$\Omega$.cm로 낮은 값을 나타내었으며, 130$\AA$ seeding 경우는 오히려 전기비저항이 증가하는 경향을 나타내었다. Cu 박막의 접착력은 seeding층의 두께가 $0\AA$에서 $130\AA$으 증가함에 따라 21N에서 27N 으로 향상되었다.

• 한국생활과학회지
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• 제17권5호
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• pp.1027-1035
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• 2008

Essentail oils and carrier oils are generally used for Aromatherapy. Therefore the toxicity, possibilities of irritations and sensitive reactions and injury of essential oils must be considered for clients and therapists. So that, in this studies a toxicity of jojoba and 4 species essential oils (fennel, mandarine, tea tree and cedarwood) were investigated by the measurement of MTT-assay and sirius red staining. Liver, kidney and brain tell were chosen for the cell viability assay and observation of morphological change. In the result, no cytotoxicity was observed on live., kidney and brain cell at concentration of 0.01 $\mu\el/m\el$ jojoba oil. And lysis and nucleus breaking were not observed at same concentration of jojoba oil on live., kidney and brain cell. fennel oil was showed 50% of cell viability and inhibited cell growth on liver, kidney and brain cell at relatively high concentration compared with the other oils. 50% of liver, kidney and brain cell viability and delayed cell growth of tea tree and mandarine oil were revealed at lower concentration than fennel oil. In cedarwood oil, 50% of liver cell viability at concentration of 0.00067 $\mu\el/m\el$ was showed, but cell viability and cell growth of kidney and beam cell were effected at the lowest concentration compared with other oils. So that, jojoba oil as using of carrier oil may be not harmful. And 3 essential oils from the fennel, tea tree and mamdarine may have very low toxicity, but cedarwood may be used carefully for inhalation. And over dosage of concentrated cedarwood oil should be not directly touched and exposured, and absolute essential oils must be diluted with carrier oils for topical and systematic massage.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 춘계종합학술대회
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• pp.1034-1037
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• 2005

Si (111) 기판 상에 전자빔 증착법으로 Ni, Cr 금속 패턴을 형성시킨 후, 그 금속 패턴 위에 대기 중에서 열 증착법으로 Zn powder를 사용하여 ZnO 나노 구조를 형성시켰다. 형성 시 기판의 온도는 500 ${\sim}$ 700 $^{\circ}$C의 범위에서 설정하였다. 금속 촉매 상에 형성된 ZnO 나노 구조와, Si 기판 상에 형성된 ZnO 나노 구조에서 각각의 형성된 나노 구조의 형상과 이에 따른 나노 구조의 특성 변화를 관찰하였다. 형성된 시료의 발광 특성은 실온에서 He-Cd laser (325 nm)를 이용하여 조사하였고, 금속 패턴 상에 형성된 나노 구조와 Si 기판 상에 형성된 나노 구조의 형상 차이를 광학 현미경과 Scanning Electron Microscope (SEM)을 이용하여 관찰하였다. 그 결과 기판의 온도가 비교적 저온일 때에는 촉매에 의한 영향을 관찰할 수 없었으나 성장 온도가 700 $^{\circ}$ 이상의 고온에서는 금속 촉매가 발광 특성 및 나노 구조의 형상에 영향을 주는 것을 알 수 있었다.

• 한국진공학회지
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• 제21권5호
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• pp.264-272
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• 2012

본 논문에서는 InGaAs 반도체에 기반한 테라헤르쯔(THz) 송/수신기(Tx/Rx) 제작을 위한 기초 연구로서, InGaAs 박막의 THz 발생 및 검출 특성에 관한 결과를 보고한다. THz 발생과 검출 특성 조사에는 각각 MBE 장비로 고온(HT) 및 저온(LT)에서 성장한 InGaAs 박막이 사용되었으며, THz 발생에는 photo-Dember 표면방출 방법이 시도되었다. HT-InGaAs 기판 위에 제작한 전송선(Ti/Au)의 가장자리에 Ti:Sapphire fs 펄스 레이저(60 ps/83 MHz)를 조사하여 THz파를 발생시켰으며, 이때 THz 검출에는 LT-GaAs가 사용되었다. 시간지연에 따른 전류신호를 Fourier 변환하여 얻은 THz 스펙트럼의 주파수 범위는 약 0.5~2 THz이었으며, 여기 레이저 출력에 대한 신호의 세기는 지수함수적 변화를 보였다. THz 검출 특성에 사용한 LT-InGaAs Rx에는 쌍극자(5/20 ${\mu}m$) 구조의 안테나가 탑재되어 있으며, 차단 주파수는 약 2 THz이었다.

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 1998년도 추계학술발표대회 초록개요집
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• pp.0-0
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• 1998

-Part I- As market needs become more various, the production of smaller quantities of a wider variety of products becomes increasingly important. In addition, in order to meet demands for more efficient production, long-term unmanned factory operation is prevailing at a remarkable pace. Within this context, laser machines are gaining increasing popularity for use in applications such as cutting and welding metallic and ceramic materials. FANUC supplies four models of $CO_2$ laser oscillators with laser power ranging from 1.5㎾ to 6㎾ on an OEM basis to machine tool builders. However, FANUC has been requested to produce laser oscillators that allow more compact and lower-cost laser machines to be built. To meet such demands, FANUC has developed six models of Slab type YAG laser oscillators with output power ranging from 150W to 2㎾. These oscillators are designed mainly fur cutting and welding sheet metals. The oscillator has an exceptionally superior laser beam quality compared to conventional YAG laser oscillators, thus providing significantly improved machining capability. In addition, the laser beam of the oscillator can be efficiently transmitted through quartz optical fibers, enabling laser machines to be simplified and made more compact. This paper introduces the features of FANUC’s developed Slab type YAG laser oscillators and their applications. - Part II - All-solid-state lasers employing laser diodes (LD) as a source of pumping solid-state laser feature high efficiency, compactness, and high reliability. Thus, they are expected to provide a new generation of processing tools in various fields, especially in automobile and aircraft industries where great hopes are being placed on laser welding technology for steel plates and aluminum materials for which a significant growth in demand is expected. Also, in power plants, it is hoped that reliability and safety will be improved by using the laser welding technology. As in the above, the advent of high-power all-solid-state lasers may not only bring a great technological innovation to existing industry, but also create new industry. This is the background for this project, which has set its sights on the development of high-power, all-solid-state lasers with an average output of over 10㎾, an oscillation efficiency of over 20%, and a laser head volume of below 0.05㎥. FANUC Ltd. is responsible for the research and development of slab type lasers, and TOSHIBA Corp. far rod type lasers. By pumping slab type Nd: YAG crystal and by using quasi-continuous wave (QCW) type LD stacks, FANUC has already obtained an average output power of 1.7㎾, an optical conversion efficiency of 42%, and an electro-optical conversion efficiency of 16%. These conversion efficiencies are the best results the world has ever seen in the field of high-power all-solid-state lasers. TOSHIBA Corp. has also obtained an output power of 1.2㎾, an optical conversion efficiency of 30％, and an electro-optical conversion efficiency of 12%, by pumping the rod type Nd: YAG crystal by continuous wave (CW) type LD stacks. The laser power achieved by TOSHIBA Corp. is also a new world record in the field of rod type all-solid-state lasers. This report provides details of the above results and some information on future development plans.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.242-242
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• 2016

Magnetite, Fe3O4, is a ferrimagnet with a cubic inverse spinel structure and exhibits a metal-insulator, Verwey, transition at about 120 K.[1] It is predicted to possess as half-metallic nature, 100% spin polarization, and high Curie temperature (850 K). Cobalt ferrite is one of the most important members of the ferrite family, which is characterized by its high coercivity, moderate magnetization and very high magnetocrystalline anisotropy. It has been reported that the CoFe2O4/Fe3O4 bilayers represent an unusual exchange-coupled system whose properties are due to the nature of the oxide-oxide super-exchange interactions at the interface [2]. In order to evaluate the effect of interface interactions on magnetic and transport properties of ferrite and cobalt ferrite, the CoFe2O4/Fe3O4 superlattices on MgO (100) substrate have been fabricated by molecular beam epitaxy (MBE) with the wave lengths of 50, and $200{\AA}$, called $25{\AA}/25{\AA}$ and $100{\AA}/100{\AA}$, respectively. Streaky RHEED patterns in sample $25{\AA}/25{\AA}$ indicate a very smooth surface and interface between layers. HR-TEM image show the good crystalline of sample $25{\AA}/25{\AA}$. Interestingly, magnetization curves showed a strong antiferromagnetic order, which was formed at the interfaces.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 제5회 학술대회 논문집 일렉트렛트 및 응용기술연구회
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• pp.61-64
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• 2003

This paper presents Bi thin films have been fabricated by atomic layer-by-layer deposition and co-deposition at an IBS method. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. Mg(100) was used as a substrate. In order to appreciate stable existing region of Bi 2212 phase with temperature and ozone pressure, the substrate temperature was varied between 655 and $820^{\circ}C$ and the highly condensed ozone gas pressure$(PO_3)$ in vacuum chamber was varied between $2.0{\times}10^{-6}$ and $2.3{\times}10^{-5}$ Torr. Bi 2212 phase appeared in the temperature range of 750 and $795^{\circ}C$ and single phase of Bi 2201 existed in the lower region than $785^{\circ}C$. Whereas, $O_3$ dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with $T_c$(onset) of about 90 K and $T_c$(zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as $CaCuO_2$ was observed in all of the obtained films.

• 한국세라믹학회지
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• 제45권8호
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• pp.472-476
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• 2008

The surface region of commercial stainless steel 304 and 316 plates has been modified through deposition of the multi-layered coatings composed of titanium film ($0.1{\mu}m$) and gold film ($1-2{\mu}m$) by an electron beam evaporation method. XRD patterns of the stainless steel plates deposited with conductive metal films showed the peaks of the external gold film and the stainless steel substrate. Surface microstructural morphologies of the stainless steel bipolar plates modified with multi-layered coatings were observed by AFM and FE-SEM images. The stainless steel plates modified with $0.1{\mu}m$ titanium film and $1{\mu}m$ gold film showed microstructure of grains of under 100 nm diameter. The external surface of the stainless steel plates deposited with $0.1{\mu}m$ titanium film and $2{\mu}m$ gold film represented somewhat grain growth of Au grains in FE-SEM image. The electrical resistance and water contact angle of the stainless steel bipolar plates modified with multi-layered coatings were examined with the thickness of the gold film.