• Title/Summary/Keyword: phase-change

검색결과 4,214건 처리시간 0.039초

Ag 도핑된 Sbx(Ge-Se-Te)100-x 박막의 개선된 상변화 특성

  • 남기현;김장한;정홍배
    • 한국진공학회:학술대회논문집
    • /
    • 한국진공학회 2011년도 제40회 동계학술대회 초록집
    • /
    • pp.181-182
    • /
    • 2011
  • Phase-change materials can be cycled by exposure to laser beam, and as a function of the pulse intensity and duration, the laser beam triggers the switching from crystalline to amorphous phase and back. In other to progress better crystallization transition and amorphization long phase-transformation data of phase-change memory (PRAM), we investigated about the effect of Sb doping and Ag ions percolating into Ge-Se-Te phase-change material. Doped Sb concentrations was determined each of 10, 20 and 30 wt%. As the Sb-doping concentration was increased, the resistivity decreased and the crystallization temperature increased. Ionization of Ag was progressed by DPSS laser (532 nm) for 1 hour. The resistivity was more decreased and the crystallization temperature was more increased in case of adding Ag layer under Sb-(Ge-Se-Te) thin film. At the every condition of thin films included Ag layer more stable states were indicated compare with just Sb-doped Ge-Se-Te thin films.

  • PDF

하부전극 구조 개선에 의한 상변화 메모리의 전기적 특성 (Electrical characteristic of Phase-change Random Access Memory with improved bottom electrode structure)

  • 김현구;최혁;조원주;정홍배
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
    • /
    • pp.69-70
    • /
    • 2006
  • A detailed Investigation of cell structure and electrical characteristic in chalcogenide-based phase-change random access memory(PRAM) devices is presented. We used compound of Ge-Sb-Te material for phase-change cell. A novel bottom electrode structure and manufacture are described. We used heat radiator structure for improved reset characteristic. A resistance change measurement is performed on the test chip. From the resistance change, we could observe faster reset characteristic.

  • PDF

수중에서 진동하는 구조물로부터 방사되는 음에 기인한 레이저 도플러 진동측정기 광선의 위상변화에 대한 분석 (Analysis of the Phase Change of a Laser Beam in a Laser Doppler Vibrometer Due To the Sound Field Radiated From Structures Vibrating Underwater)

  • 길현권
    • 한국음향학회지
    • /
    • 제27권4호
    • /
    • pp.178-182
    • /
    • 2008
  • 레이저 도플러 진동 측정기를 사용하여 수중 구조물의 진동을 측정하는 경우, 구조물의 표면으로부터 레이저 광선이 겪는 위상 변화를 감지함으로써 진동을 측정하게 된다. 이 경우 레이저 광선은 진동하는 구조물 표면으로부터 방사되는 방사 음장을 통과하게 되며, 이러한 방사 음장에 의한 굴절률 변화에 의하여서도 레이저 광선은 위상 변화를 겪게 된다. 구조물의 진동을 측정하기 위하여서는 표면 진동 자체에 의한 레이저 광선의 위상 변화만을 감지하여야 하지만, 방사 음장의 굴절률 변화에 의한 레이저 광선의 위상 변화가 추가로 발생하여 진동 측정값에 오차를 발생시키게 된다. 이러한 오차는 공기중에서는 무시할 수 있을 정도로 작은 값이지만, 특히 수중에서는 구조물의 진동 측정값에 상당한 오차를 발생시킬 수 있게 된다. 본 논문에서는 수중에서의 방사 음장에 의한 레이저 광선의 위상 변화를 분석하였다. 예로써 수중에서 진동하는 무한 원통형 구조물로부터 방사 음장에 의한 레이저 광선의 위상 변화를 예측하고 분석하였다.

SRM의 여자방식에 따른 소음특성 해석 (An Analysis of Noise Characteristics According to the Excitation Method of SRM)

  • 문재원;오석규;안진우
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
    • /
    • 제49권9호
    • /
    • pp.565-571
    • /
    • 2000
  • SRM has been applied to many commercial applications that require economical advantages and high performance abilities. But it has some drawbacks such as acoustic noise due to the abrupt change of mmf level when commutation. The abrupt change of a phase excitation produces mechanical stresses and it results in torque ripple and noise. This paper deals with an analysis of vibration and noise in SRM drive. Several types of excitation method are taken into account. The 1-phase and 2-phase excitation technique of short-pitch winding 2-phase excitation technique of full-pitch winding are tested. The acoustic noise is reduced remarkably through the sequential phase excitation in the 2-phase excitation. It is because that the scheme reduces abrupt change of excitation level by distributed balanced excitation with free-wheeling during commutation.

  • PDF

GeSbTe계 이중층의 상변화 특성에 미치는 열처리 온도 효과 (Effect of Annealing Temperature on Phase-change Characteristics of GeSbTe-based Bilayers)

  • 윤회진;방기수;이승윤
    • 한국전기전자재료학회논문지
    • /
    • 제30권2호
    • /
    • pp.86-90
    • /
    • 2017
  • This work reports the phase-change behavior and thermal stability of doped GeSbTe/GeSbTe bilayers. We prepared the bilayers using RF sputtering, and annealed them at annealing temperature ranging from $100^{\circ}C$ to $400^{\circ}C$. The sheet resistance of the bilayer decreased and saturated with increasing annealing temperature, and the saturated value was close to that of pure GeSbTe film. The surface of the bilayer roughened at $400^{\circ}C$, which corresponds to the surface roughening of doped GeSbTe film. Mixed phases of face-centered cubic and hexagonal close-packed crystalline structures were identified in the bilayers annealed at elevated temperature. These results indicate that the phase-change behavior of the bilayer depends on the concurrent phase-transitions of the two GeSbTe-based films. The dopants in the doped GeSbTe film were diffused out at annealing temperatures of $300^{\circ}C$ or higher, which implies that the thermal stability of the bilayer should be considered for its application in phase-change electronic devices.

GeSbTe 상변화 박막의 선택적 에칭 특성 (Selective Wet-Etching Properties of GeSbTe Phase-Change Films)

  • 김진홍;임정식;이준석
    • 정보저장시스템학회논문집
    • /
    • 제3권3호
    • /
    • pp.118-122
    • /
    • 2007
  • Phase-change wet-etching technology using GeSbTe phase-change films is developed. Selective etching between an amorphous and a crystalline phase can be carried out with an alkaline etchant of NaOH. Etching selectivity is dependent not only on the concentration of the alkaline etchant but also on the film structure. Specifically, metal films for heat control cause marked effects on the etching properties of GeSbTe film. Surviving amorphous pits can be obtained with Al metal layer, however etched amorphous pits are seen with Ag metal layer. An opposite selective etching behavior can be observed between samples with two different metal layers.

  • PDF

Sb-doped Ag/Ge-Se-Te 박막의 상변화 특성 연구 (A Study of Phase-change Properties of Sb-doped Ag/Ge-Se-Te thin films)

  • 남기현;정원국;박주현;정홍배
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2010년도 하계학술대회 논문집
    • /
    • pp.347-347
    • /
    • 2010
  • In other to progress better crystallization transition and long phase-transformation data of phase-change memory (PRAM), we investigated about the effect of Sb doping and Ag ions percolating into Ge-Se-Te phase-change material. Doped Sb concentrations was determined each of 10 wt%, 20 wt% and 30 wt%. As the Sb-doping concentration was increased, the resistivity decreased and the crystallization temperature increased. Ionization of Ag was progressed by DPSS laser (532 nm) for 1 hour. The resistivity was more decreased and the crystallization temperature was more increased in case of adding Ag layer under Sb-(Ge-Se-Te) thin film. At the every condition of thin films included Ag layer more stable states were indicated compare with just Sb-doped Ge-Se-Te thin films.

  • PDF

유한요소법을 이용한 순수 물의 상변화 과정에 대한 수치해석 (Finite Element Analysis on Phase-Change Process of Pure Water)

  • 홍영대;차경석;서석진;박찬국
    • 한국전산유체공학회지
    • /
    • 제7권4호
    • /
    • pp.1-7
    • /
    • 2002
  • The phase-change transformation processes are relevant in many engineering applications. In particular, this phenomenon plays an important role in the extraction and fabrication operations in the metallurgical industry. The control of the heat transfer and fluid flow patterns is important to achieve casting quality and competitive production times. In the present study, a simple finite-element algorithm is developed for solid-liquid phase change problems. Natural convection in the liquid phase due to the temperature dependency of water density is considered by a numerical model. The predictions are compared with measurements by the particle image velocimetry(PIV). to show that the calculation results are in good agreement with the experiment results.

Design of a Plasmonic Switch Using Ultrathin Chalcogenide Phase-change Material

  • Lee, Seung-Yeol
    • Current Optics and Photonics
    • /
    • 제1권3호
    • /
    • pp.239-246
    • /
    • 2017
  • A compact plasmonic switching scheme, based on the phase change of a thin-film chalcogenide material ($Ge_2Sb_2Te_5$), is proposed and numerically investigated at optical-communication wavelengths. Surface plasmon polariton modal analysis is conducted for various thicknesses of dielectric and phase-change material layers, and the optimized condition is induced by finding the region of interest that shows a high extinction ratio of surface plasmon polariton modes before and after the phase transition. Full electromagnetic simulations show that multiple reflections inside the active region may conditionally increase the overall efficiency of the on/off ratio at a specific length of the active region. However, it is shown that the optimized geometrical condition, which shows generally large on/off ratio for any length of active region, can be distinguished by observing the multiple-reflection characteristic inside the active region. The proposed scheme shows an on/off switching ratio greater than 30 dB for a length of a few micrometers, which can be potentially applied to integrated active plasmonic systems.

Melting Heat Transfer Characteristics of Plural Phase Change Microcapsules Slurry Having Different Diameters

  • Kim, Myoung-Jun;Kim, Myoung-Hwan
    • Journal of Advanced Marine Engineering and Technology
    • /
    • 제28권8호
    • /
    • pp.1225-1238
    • /
    • 2004
  • The present study has been performed for obtaining the melting heat transfer enhancement characteristics of water mixture slurries of plural microcapsules having different diameters encapsulated with solid-liquid phase change material(PCM) flowing in a pipe heated under a constant wall heat flux condition. In the turbulent flow region, the friction factor of the present PCM slurry was to be lower than that of only water flow due to the drag reducing effect of the PCM slurry. The heat transfer coefficient of the PCM slurry flow in the pipe was increased by both effects of latent heat involved in phase change process and microconvection around plural microcapsules with different diameters. The experimental results revealed that the average heat transfer coefficient of the PCM slurry flow was about 2~2.8 times greater than that of a single phase of water.