• 제목/요약/키워드: phase change materials

검색결과 823건 처리시간 0.045초

Synthesis and Analysis of Ge2Sb2Te5 Nanowire Phase Change Memory Devices

  • 이준영;김정현;전덕진;한재현;여종석
    • 한국진공학회:학술대회논문집
    • /
    • 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
    • /
    • pp.222.2-222.2
    • /
    • 2015
  • A $Ge_2Sb_2Te_5$ nanowire (GST NW) phase change memory device is investigated with Joule heating electrodes. GST is the most promising phase change materials, thus has been studied for decades but atomic structure transition in the phase-change area of single crystalline phase-change material has not been clearly investigated. We fabricated a phase change memory (PCM) device consisting of GST NWs connected with WN electrodes. The GST NW has switching performance with the reset/set resistance ratio above $10^3$. We directly observed the changes in atomic structure between the ordered hexagonal close packed (HCP) structure and disordered amorphous phase of a reset-stop GST NW with cross-sectional STEM analysis. Amorphous areas are detected at the center of NW and side areas adjacent to heating electrodes. Direct imaging of phase change area verified the atomic structure transition from the migration and disordering of Ge and Sb atoms. Even with the repeated phase transitions, periodic arrangement of Te atoms is not significantly changed, thus acting as a template for recrystallization. This result provides a novel understanding on the phase-change mechanism in single crystalline phase-change materials.

  • PDF

FCS 가변형 몰드 생산을 위한 PCM 분석 (Analysis of Phase Change Materials for Production of Changable Mold for Free-form Concrete Segment)

  • 이동훈;김선국
    • 한국건축시공학회:학술대회논문집
    • /
    • 한국건축시공학회 2014년도 춘계 학술논문 발표대회
    • /
    • pp.150-151
    • /
    • 2014
  • A mold of free-form concrete segment can be used only one time. Thus, the construction duration and cost are increased. The materials of the mold such as wood and metal have limitations due to the implementation and reuse. The review of the material of the mold for free-form concrete segment is needed to reduce duration and production cost. Phase change material can be used both to implement free-shape by heating and to produce mold after cooling. After using Phase change material can be re-used to mold by heating. The scope of this study is many kind of phase change materials for molding. The aim of this study is to analyze the phase change materials for production of changable mold for free-form concrete segment. In this study, the paraffin wax that is melted at 64℃ was selected by considering both the energy efficiency and the weather of Korea.

  • PDF

Phase Change Characteristics of Sb-Based Phase Change Materials

  • Park, Sung-Jin;Kim, In-Soo;Kim, Sang-Kyun;Choi, Se-Young
    • 한국재료학회지
    • /
    • 제18권2호
    • /
    • pp.61-64
    • /
    • 2008
  • Electrical optical switching and structural transformation of $Ge_{15}Sb_{85}$, $Sb_{65}Se_{35}$ and N2.0 sccm doped $Sb_{83}Si_{17}$ were studied to investigate the phase change characteristics for PRAM application. Sb-based materials were deposited by a RF magnetron co-sputtering system and the phase change characteristics were analyzed using an X-ray diffractometer (XRD), a static tester and a four-point probe. Doping Ge, Se or Si atoms reinforced the amorphous stability of the Sb-based materials, which affected the switching characteristics. The crystallization temperature of the Sb-based materials increased as the concentration of the Ge, Se or Si increased. The minimum time of $Ge_{15}Sb_{85}$, $Sb_{65}Se_{35}$ and N2.0 sccm doped $Sb_{83}Si_{17}$ for crystallization was 120, 50 and 90 ns at 12 mW, respectively. $Sb_{65}Se_{35}$ was crystallized at $170^{\circ}C$. In addition, the difference in the sheet resistances between amorphous and crystalline states was higher than $10^4{\Omega}/{\gamma}$.

c-AFM 기술을 이용한 나노급 상변화 소자 특성 평가에 대한 연구 (The study about phase phase change material at nano-scale using c-AFM method)

  • 홍성훈;이헌
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2010년도 하계학술대회 논문집
    • /
    • pp.57-57
    • /
    • 2010
  • In this study, nano-sized phase change materials were evaluated using nanoimprint lithography and c-AFM technique. The 200nm in diameter phase change nano-pillar device of GeSbTe, AgInSbTe, InSe, GeTe, GeSb were successfully fabricated using nanoimprint lithography. And the electrical properties of the phase change nano-pillar device were evaluated using c-AFM with pulse generator and voltage source.

  • PDF

상전이 마이크로캡슐 재료의 축열특성 (The characteristics of microencapsulated phase-change materials)

  • 임대우
    • 한국복합재료학회:학술대회논문집
    • /
    • 한국복합재료학회 2003년도 춘계학술발표대회 논문집
    • /
    • pp.53-56
    • /
    • 2003
  • The objective of this research is to investigate the thermal behavior of microencapsulated phase-change materials(MEPCM), and a shell of melamine-formaldehyde. These PCM materials were tested using DSC and thermal data station. Fabrics with enhanced thermal properties were prepared by padding the fabrics with the microcapsules containing PCM and acryl binder. The rate of temperature increase was significantly decreased as the amount of MEPCM added on the surface of the fabrics increased.

  • 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

Phase Change Characteristics of SnXSe100-X Thin Films by RF-magnetron Sputtering

  • 김상균;최세영
    • 한국재료학회지
    • /
    • 제19권4호
    • /
    • pp.203-206
    • /
    • 2009
  • $Sn_XSe_{100-X}$ (15|X|30) alloys have been studied to explore their suitability as phase change materials for nonvolatile memory applications. The phase change characteristics of thin films prepared by a Radio Frequency (RF) magnetron co-sputtering system were analyzed by an X-ray diffractometer and 4-point probe measurement. A phase change static tester was also used to determine their crystallization under the pulsed laser irradiation. X-ray diffraction measurements show that the transition in sheet resistance is accompanied by crystallization. The amorphous state showed sheet resistances five orders of magnitude higher than that of the crystalline state in $Sn_XSe_{100-X}$ (x = 15, 20, 25, 30) films. In the optimum composition, the minimum time of $Sn_XSe_{100-X}$ alloys for crystallization was 160, 140, 150, and 30ns at 15mW, respectively. The crystallization temperature and the minimum time for crystallization of thin films were increased by increasing the amount of Sn, which is correlated with the activation energy for crystallization.

Influence of Sn/Bi doping on the phase change characteristics of $Ge_2Sb_2Te_5$

  • Park T.J.;Kang M.J.;Choi S.Y.
    • 정보저장시스템학회논문집
    • /
    • 제1권1호
    • /
    • pp.93-98
    • /
    • 2005
  • Rewritable optical disk is one of the essential data storage media in these days, which takes advantage of the different optical properties in the amorphous and crystalline states of phase change materials. As well known, data transfer rate is one of the most important parameter of the phase change optical disks, which is mostly limited by the crystallization speed of recording media. Therefore, we doped Sn/Bi to $Ge_2Sb_2Te_5$ alloy in order to improve the crystallization speed and investigated the dependence of phase change characteristics on Sn/Bi doping concentration. The Sn/Bi doped $Ge_2Sb_2Te_5$ thin film was deposited by RF magnetron co-sputtering system and phase change characteristics were investigated by X-ray diffraction (XRD), static tester, UV-visible spectrophotometer, electron probe microanalysis (EPMA), inductively coupled plasma mass spectrometer (ICP-MS) and atomic force microscopy (AFM). Optimum doping concentration of Bi and Sn were 5${\~}$6 at.$\%$ and the minimum time for crystallization was below than 20 ns. This improvement is correlated with the simple crystalline structure of Sn/Bi doped $Ge_2Sb_2Te_5$ and the reduced activation barrier arising from Sn/Bi doping. The results indicate that Sn/Bi might play an important role in the transformation kinetics of phase change materials..

  • PDF

상변화 메모리 응용을 위한 $Ge_{1}Se_{1}Te_{2}$ 박막의 셀 구조에 따른 전기적 특성 (Electrical characteristic for Phase-change Random Access Memory according to the $Ge_{1}Se_{1}Te_{2}$ thin film of cell structure)

  • 나민석;임동규;김재훈;최혁;정홍배
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 2007년도 제38회 하계학술대회
    • /
    • pp.1335-1336
    • /
    • 2007
  • Among the emerging non-volatile memory technologies, phase change memories are the most attractive in terms of both performance and scalability perspectives. Phase-change random access memory(PRAM), compare with flash memory technologies, has advantages of high density, low cost, low consumption energy and fast response speed. However, PRAM device has disadvantages of set operation speed and reset operation power consumption. In this paper, we investigated scalability of $Ge_{1}Se_{1}Te_{2}$ chalcogenide material to improve its properties. As a result, reduction of phase change region have improved electrical properties of PRAM device.

  • PDF

상 변화 메모리 재료 내의 Ga 주입에 미치는 GaGe 스퍼터링 전력의 영향 (Effect of GaGe Sputtering Power on Ga Doping in Phase Change Memory Materials)

  • 정순원;이승윤
    • 한국전기전자재료학회논문지
    • /
    • 제28권5호
    • /
    • pp.285-290
    • /
    • 2015
  • The phase change memory material is an active element in phase change memory and exhibits reversible phase transition behavior by thermal energy input. The doping of the phase change memory material with Ga leads to the increase of its crystallization temperature and the improvement of its amorphous stability. In this study, we investigated the effect of GaGe sputtering power on the formation of the phase change memory material including Ga. The deposition rate linearly increased to a maximum of 127 nm and the surface roughness remained uniform as the GaGe sputtering power increased in the range from 0 to 75 W. The Ga concentration in the thin film material abruptly increased at the critical sputtering power of 60 W. This influence of GaGe sputtering power was confirmed to result from a combined sputtering-evaporation process of Ga occurring due to the low melting point of Ga ($29.77^{\circ}C$).