• 제목/요약/키워드: sublimation method

검색결과 159건 처리시간 0.026초

Defect formation mechanism of 6H-SiC crystals grown by sublimation method

  • Kim, Hwa-Mok;Kyung Joo;Auh, Keun-Ho
    • 한국결정성장학회:학술대회논문집
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    • 한국결정성장학회 1998년도 PROCEEDINGS OF THE 15TH KACG TECHNICAL MEETING-PACIFIC RIM 3 SATELLITE SYMPOSIUM SESSION 4, HOTEL HYUNDAI, KYONGJU, SEPTEMBER 20-23, 1998
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    • pp.35-40
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    • 1998
  • There have two kinds of defects, planar defects and vertical defects which were called micropipes in SiC bulk crystals grown by a sublimation method. We could decrease these defects by adding a little piece of Si in the SiC powder or using Ta cylinder in the crucible. so were report the dependence of these defects in a wafer on silicon/carbon ratio in this paper. The chemical species sublimed from SiC powder is affected by carbon from the graphite wall of the crucible. It is important to control the chemical species on the substrate.

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다결정실리콘 표면 미세가공 기술을 위한 점착 방지법들의 성능 비교 (The Comparison of Stiction Results of Anti-Stiction Methods for Polysilicon Surface Micromachining)

  • 이윤재;한승오;박정호
    • 센서학회지
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    • 제9권3호
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    • pp.233-241
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    • 2000
  • 본 연구에서는 동일한 테스트 구조물을 사용하여 현재 다결정실리콘 표면 미세가공 기술에서 널리 사용되고 있는 여러 가지 점착 방지법들의 성능을 비교하였다. 테스트 구조물로는 다양한 폭과 길이를 갖는 일반적인 cantilever와 dimple, antistiction tip, plate를 가지는 cantilever를 사용하였으며 구조물 형태에 따른 점착 방지 결과를 관찰하였다. 희생층 제거 후 구조물과 기판의 점착을 결정하는 건조과정에서는 증발법과 승화건조법을 사용하였다. 증발법에서는 methanol, IPA, DI water 등을 여러 최종 세척액으로 사용하여 표면장력과 세척 온도에 따른 점착 방지 결과를 비교하였다. 승화건조법에서는 중간 세척액으로 methanol을 사용하였다. 그리고 동일한 실험조건으로 stress gradient가 있는 동일한 구조물을 사용하여 stress gradient에 의한 점착 방지 결과를 관찰하였다. 결론적으로 승화건조법이 여러 가지 증발법보다 우수한 결과를 보여주었고 다결정 실리콘 표면 미세가공 기술로 미세 구조물을 부양시킬 때 승화건조법이 가장 우수한 방법이라고 사료된다.

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소설과 말기 암환자를 통해 본 한국인의 죽음의 의미

  • 전혜원;김분한
    • 호스피스학술지
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    • 제3권2호
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    • pp.34-54
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    • 2003
  • Every one experiences death one day, however no one can knows exactly what it is because people can not experience death until it comes, it is therefore impossible to judge correctly on the phenomenon of the death. On the whole, man experiences indirect death through the mass communications such as TV drama, fiction, magazine etc because those methods can easily access by every one. In addition to this, people usually acquire the negative awareness of death through the dramatic change of story like dying of cancer for dramatic effect by giving scare and fear to the cancers. The purpose of this study is to provide basic information on the spiritual care that enables the facing death patients to accept death as a part of life and divert hope from scare about after death by comparing and analyzing of two aspects of death meaning I.e, Korean fiction and the end stage cancer patients. Additionally, for medical staff to understand the facing death cancer patients by making to aware patients correctly and provide the better quality of care. The study was performed from September 28, 2002 to February, 28 2003. The materials of this study were collected by direct data obtained from observation, interviews, note and diary of end stage of cancer patients and written materials acquired from Korean contemporary fiction. Participants of this study were 4 end stage cancer patients including 2 lung cancer patients, 1 liver cancer patient and 1 esophagus cancer patient. The methodology used in this study was divided into two types; Huberman & Miles methodology was used for fiction to find and categorize subject, and Colaizzi, one of phenomenological methodology was used for end stage cancer patients to find the major meaning, subject and categorization. 1.The death investigated in the fiction, was found as a progress of negative emotion, acceptance and sublimation, life related subjects in the negative emotion were tenacity for life, anxiety, lingering attachment, responsibility, abandonment and death related subjects were shock, isolation, fear, scare and rejection. Acceptance related subjects were acceptance, destiny, secularism, preparation and arrangement, and sublimation related subjects were sublimation through Christian and Buddhism. 2.The death showed in the participants was negative emotion, acceptance and sublimation, life related subjects were repentance, anxiety, responsibility and hopelessness, and death related subjects were dejection, solitude, anger, fear and scare. The acceptance was a type of religious acceptance that admitted instantly by reaching an understanding with the God, and death was accepted as a progress of preparation, arrangement, acceptance and hope. Sublimation related subjects were Christian sublimation and relief or destiny incurred from self-reflective sublimation through communications and thoughts. 3.The death in view of fiction and participants were positively accepted both death and negative emotion, and the study disclosed the fact that death was sublimated dependent on religion. 4.The progress of negative emotion, acceptance and sublimation was disclosed more complicated and various in the real end stage cancer patients and acceptance only found in the patients on the form of religious acceptance, according to the results compared with fiction and real end stage cancer patients. The death showed in the fiction was standardized, gradated and similar progress with psychological status of Kubler-Ross. However, death in the participants was showed complex and various feelings simultaneously, and sometimes they accepted death positively. The sublimation through religion was found in Buddhism and Christian in the fiction and mostly Christian in the participants due to a number of Hospice patients. It was found that negative emotion various types of death was more found in the participants than fiction. It is therefore necessary to study on the response of death in various types. In the participants death was incurred more systematic and variously, we knew that nursing practice focused on experience of participants is required and reality on death is much profound than we analyzed and presented, lots of situations and reactions should be premised because we can not completely rule out the negligence possibility of care mediation of participants. In caring for the facing death patients, we discovered and confirmed again through this study that the spiritual care should be needed as a mediation method.

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승화법에 의한 CdSe 성장과 특성 (Growth and characterites for CdSe single crystal grown by using sublimation method)

  • 홍광준;백승남;;김도선
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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    • pp.180-181
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    • 2006
  • CdSe single crystal was grown by sublimation method in the two-step vertical electric furnace. This CdSe single crustal had hexagonal structure whose lattice constants of $a_0$ and $c_0$ were measured $4.299\;{\AA}$ and $7.009\;{\AA}$ by extrapolation method, respectively. CdSe single crystal was n-type semiconductor values were measured from Hall data by Van der Pauw method in the room temperature. Mobility tends to increase in proportion to $T^{3/2}$ from 33K to 130K due to impurity scattering. but mobility tends to decrease in proprtion to $T^{-3/2}$ from 130K to 293K due to lattice scattering. CdSe thin film was made by electron beam evaporation technique had also hexagonal structure. The grain size of this thin film was grown to $1{\mu}m$ as a result of annealing in the vapor of Ar or Cd. Annealde CdSe thin film was n-type semiconductor whose carrier density had about $7{\times}10^{12}cm^{-3}$ and its mobility had about $1.6{\times}10^3cm^2/V$ sec at room temperature.

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고성능 액체 크로마토그래피를 이용한 고삼 중의 oxymatrine 분석에 관한 연구 (Determination of oxymatrine in Sophora Radix by High Performance Liquid Chromatography)

  • 양승권;윤영자;남궁미옥
    • 분석과학
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    • 제17권4호
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    • pp.289-294
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    • 2004
  • 고성능 액체 크로마토그래피를 이용하여 고삼 중의 oxymatrine을 분석하였다. acetonitrile을 포함하는 완충용액과 $C_{18}$컬럼을 이용한 역상 크로마토그래피를 수행하였다. Oxymatrine의 분리는 215 nm에서 UV흡수가 관측되었다. 고삼 중의 oxymatrine의 추출은 다양한 용매와 다양한 추출방법을 사용한 결과, 마쇄한 고삼의 최적의 추출 효율은 $80^{\circ}C$에서 50% ethanol로 5시간 동안 환류가열 하였을 때 가장 높은 효율을 보였다. 대부분의 추출 방법은 복잡한 전처리를 필요로 하지만, 본 연구에서는 승화 추출법으로 복잡한 전처리를 제외시킨 추출법을 고안하였다. 승화 추출은 높은 진공 ($1{\times}10^{-3}$ torr) 과 높은 온도 ($200^{\circ}C$)에서 수행되었다. 승화 추출법을 사용한 추출 효율은 다른 추출 방법들과 비교해서 전처리 과정을 거치지 않은 장점은 있었으나 추출 효율이 좀 낮았다.

CST 승화법을 이용한 p-type 4H-SiC(0001) 에픽텍셜층 성장과 이를 이용한 MESFET 소자의 전기적 특성 (Epitaxial Layer Growth of p-type 4H-SiC(0001) by the CST Method and Electrical Properties of MESFET Devices with Epitaxially Grown Layers)

  • 이기섭;박치권;이원재;신병철
    • 한국전기전자재료학회논문지
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    • 제20권12호
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    • pp.1056-1061
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    • 2007
  • A sublimation epitaxial method, referred to as the Closed Space Technique (CST) was adopted to produce thick SiC epitaxial layers for power device applications. In this study, we aimed to systematically investigate surface morphologies and electrical properties of SiC epitaxial layers grown with varying a SiC/Al ratio in a SiC source powder during the sublimation growth using the CST method. The surface morphology was dramatically changed with varying the SiC/Al ratio. When the SiC/Al ratio of 90/1 was used, the step bunching was not observed in this magnification and the ratio of SiC/Al is an optimized range to grow of p-type SiC epitaxial layer. It was confirmed that the acceptor concentration of epitaxial layer was continuously decreased with increasing the SiC/Al ratio. 4H-SiC MESFETs haying a micron-gate length were fabricated using a lithography process and their current-voltage performances were characterized. It was confirmed that the increase of the negative voltage applied on the gate reduced the drain current, showing normal operation of FET device.

Growth rate and growth steps of 6H-SiC single crystals in the sublimation process

  • Kang, Seung-Min;Lim, Chang-Sung;Auh, Keun-Ho
    • 한국결정성장학회지
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    • 제11권4호
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    • pp.166-169
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    • 2001
  • 6H-SiC bulk crystals were grown by sublimation method with different conditions in term of gaseous pressures ad source temperatures. In order to optimize the growth rate, pressure at growth period and source and substrate temperatures were investigated as experimental variables. the results were compared with each other and finally the optimum growth conditions were discussed. Furthermore the relation of the growth steps and defects formation was evaluates in the point of reducing the micropipes. Subsequently the growth steps and defects formation was evaluated in the point of reducing the micropipes. Subsequently the growth steps were observed leading to the lower step height with the lower growth rate.

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난류촉진체에 의한 전자칩의 열전달촉진에 관한 연구 (Heat transfer enhancement in electronic modules using a turbulence promoter)

  • 박시우;정인기
    • 설비공학논문집
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    • 제11권6호
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    • pp.861-870
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    • 1999
  • An experimental study was carried out to investigate the effects of using various shapes of turbulence promoter on the heat-transfer enhancement of 2-D and 3-D arrays of rectangular modules in a rectangular channel for design of noiseless and low-powered cooling fan in the electronic systems. Measurements of heat/mass transfer coefficients were made using a naphthalene sublimation technique, and the friction factors were measured for Reynolds numbers in the range$3.3{\time}10^3$~$1.6{\time}10^4$. Flow visualization was peformed by oil-film method. It was found that heat transfer and pressure drop increased remarkably due to the existence of the promoter. The results of the performance evaluation based on equal pumping power were showed that substantial heat-transfer enhancement was obtained at low Reynolds number range by use of a turbulence promoter.

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