• 제목/요약/키워드: doping material

검색결과 792건 처리시간 0.031초

Phenomenological Theory of Superconductivity and Magnetism in Ho$_{1-x}Dy_xNi_2B_2C$

  • Doh, Hyeon-Jin;Sigrist, Manfred;Cho, B.K.;Lee, Sung-Ik
    • 한국초전도학회:학술대회논문집
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    • 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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    • pp.196-199
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    • 1999
  • The coexistence of the superconductivity and magnetism in the Ho1-xDyxNi2B2C is studied by using Ginzburg-Landau theory. This material violates the standard do Gennes scaling showing the coexistence and complex interplay of superconducting and magnetic order yielding an anomalous phase diagram. We propose a phenomenological model which includes two magnetic and two superconducting order parameters accounting for the multi-band structure of this material. We describe the magnetic fluctuations and order and demonstrate that they lead to anomalous behavior of the upper critical field. The doping dependence of Tc in Ho1-xDyxNi2B2C showing a reentrance behavior are analyzed yielding a very good agreement with experimental data.

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3차원 나노 다공성 그래핀의 제조와 응용 (Three-dimensional Nanoporous Graphene-based Materials and Their Applications)

  • 정현;강예인
    • 세라미스트
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    • 제22권3호
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    • pp.243-255
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    • 2019
  • Graphene, a two-dimensional material with a single atomic layer, has recently become a major research focus in various applications such as electronic devices, sensors, energy storage, catalysts, and adsorbents, because of its large theoretical surface area, excellent electrical conductivity, outstanding chemical stability, and good mechanical properties. Recently, 3D nanoporous graphene structures have received tremendous attention to expand the application of 2D graphene. Here, we overview the synthesis of 3D nanoporous graphene network structure with two-dimensional graphite oxide sheets, the control of porous parameters such as specific surface area, pore volume and pore size etc, and the modification of electronic structure by heteroatom doping along with its various applications. The 3D nanoporous graphene shows superior performance in diverse applications as a promising key material. Consequently, 3D nanoporous graphene can lead the future for advanced nanotechnology.

AIGaN/GaN 이종접합 디바이스를 위한 GaN 에피층의 전기적 특성 (Electrical Characteristics of GaN Epi Layer on Sapphire Substrates for AIGaN/GaN Heterostructures)

  • 문도성
    • 한국전기전자재료학회논문지
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    • 제15권7호
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    • pp.591-596
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    • 2002
  • In this work, epitaxial GaN is grown on sapphire substrate in AlGaN/GaN heterostructures. Deliberate oxygen doping of GaN grown by MOVPE has been studied. The electron concentration increased as a function of the square root of the oxygen partial Pressure. Oxygen is a shallow donor with a thermal ionization energy of $27\pm2 meV$ measured by temperature dependent Hall effects. A compensation ratio of $\theta$=0.3~0.4 was determined from Hall effect measurements. The formation energy of $O_N$ of $E^F$ =1.3eV determined from the experimental data, is lower than the theoretically predicted vague.

P형 우물 영역에 따른 4H-SiC DMOSFETs의 스위칭 특성 분석 (Effect of P-Base Region on the Transient Characteristics of 4H-SiC DMOSFETs)

  • 강민석;안정준;성범식;정지환;구상모
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2010년도 하계학술대회 논문집
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    • pp.352-352
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    • 2010
  • Silicon Carbide (SiC) power device possesses attractive features, such as high breakdown voltage, high-speed switching capability, and high temperature operation. In general, device design has a significant effect on the switching characteristics. In this paper, we report the effect of the P-base doping concentration ($N_{PBASE}$) on the transient characteristics of 4H-SiC DMOSFETs. By reducing $N_{PBASE}$, switching time also decreases, primarily due to the lowered channel resistance. It is found that improvement of switching speed in 4H-SiC DMOSFETs is essential to reduce the and channel resistance. Therefore, accurate modeling of the operating conditions are essential for the optimization of superior switching performance.

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도핑량에 따른 다공성 3C-SiC 박막의 전기 및 광학적 특성 (Electrical and optical characteristics of porous 3C-SiC thin films with dopants)

  • 김강산;정귀상
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2010년도 하계학술대회 논문집
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    • pp.27-27
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    • 2010
  • This paper describes the electrical and optical characteristics of $N_2$ doped porous 3C-SiC films. Average pore diameter is about 30 nm and etched area was increased with $N_2$ doping rate. The mobility was dramatically decreased in porous 3C-SiC. The band gaps of polycrystalline 3C-SiC films and doped porous 3C-SiC were 2.5 eV and 2.7 eV, respectively.

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금속(Al, Cr, Ni)의 일함수를 고려한 쇼트키 장벽 트랜지스터의 전기-광학적 특성 (Metal work function dependent photoresponse of schottky barrier metal-oxide-field effect transistors(SB MOSFETs))

  • 정지철;구상모
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2010년도 하계학술대회 논문집
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    • pp.355-355
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    • 2010
  • We studied the dependence of the performance of schottky barrier metal-oxide-field effect transistors(SB MOSFETs) on the work function of source/drain metals. A strong impact of the various work functions and the light wavelengths on the transistor characteristics is found and explained using experimental data. We used an insulator of a high thickness (100nm) and back gate issues in SOI substrate, subthreshold swing was measured to 300~400[mV/dec] comparing with a ideal subthreshold swing of 60[mV/dec]. Excellent characteristics of Al/Si was demonstrated higher on/off current ratios of ${\sim}10^7$ than others. In addition, extensive photoresponse analysis has been performed using halogen and deuterium light sources(200<$\lambda$<2000nm).

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청색형광재료와 황색인광 재료를 이용한 OLEDs의 전기 및 광학적 특성 (Electrical and Optical Properties of Organic Light Emitting Devices Using Blue Fluorescent and Orange Phosphorescent Materials)

  • 서유석;문대규
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2010년도 하계학술대회 논문집
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    • pp.155-155
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    • 2010
  • We have investigated organic light-emitting devices by doping phosphorescent orange and fluorescent blue emitters into the separate layers of single host. The electroluminescence spectra and current efficiency were strongly dependent on the location of each doped layers. The luminance-voltage (L-V) characteristics of the device2 (ITO/Hole Transport Layer/Orange Phosphorescent emissive layer/Blue Fluorescent emissive layer/Electron Transport Layer/liF/Al) showed the maximum current efficiency of 19.5 cd/A.

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(Zn1-xCax)2SiO4:Mn 녹색 형광체의 농도 변화에 따른 발광특성 (Luminescent Properties of (Zn1-xCax)2SiO4:Mn,Al Green Phosphors for Various Concentration)

  • 유일
    • 한국전기전자재료학회논문지
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    • 제23권4호
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    • pp.323-326
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    • 2010
  • $(Zn_{1-x}Ca_x)_2SiO_4$:Mn phosphors doped with Ca were synthesized by solid state reaction method. $(Zn_{1-x}Ca_x)_2SiO_4$:Mn phosphors showed XRD patterns of Willemite structure. Also, $CaSiO_3$ structure and new peak near 610 nm in $(Zn_{1-x}Ca_x)_2SiO_4$:Mn with increasing value of x were observed from XRD and PL. The new peak near 610 nm in $(Zn_{1-x}Ca_x)_2SiO_4$:Mn with doping Ca was attributed to formation of $CaSiO_3$.

Long-term Testing and Analysis of a ScSZ/LaSrCuFe Cell

  • Wackerl, Jurgen;Peck, Dong-Hyun;Markus, Torsten
    • 한국세라믹학회지
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    • 제45권12호
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    • pp.788-795
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    • 2008
  • An electrolyte supported SOFC cell was tested at $800^{\circ}C$ in air for 3600 h with an applied current density of $200\;mA/cm^2$ to examine possible cathode degradation issues. A scandium- stabilized zirconia (ScSZ) with additional manganese doping (ScSZ: Mn) was used as electrolyte. A strontium and copper-doped lanthanum ferrite (LaSrCuFe) and platinum were used as cathode and quasi-anode material, respectively. The DC resistance was logged over the complete testing period. Additionally, impedance spectroscopy was used from time to time to track changes of the cell in-situ. Post-test analysis of the cell using methods like scanning electron microscopy imaging and other electrochemical testing methods allow the identification of different degradation sources. The results indicate a promising combination of electrolyte and cathode material in terms of chemical compatibility and electrical performance.

비휘발성 SNOSFET 기억소자의 동작특성에 관한 전산모사 (Computer Simulation on Operating Characteristics of Nonvolatile SNOSFET Memory Devices)

  • 김주연;이상배;이영희;서광열
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 1992년도 추계학술대회 논문집
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    • pp.14-17
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    • 1992
  • To analyze Nonvolatile SNOSFET(polySilicon-Nitride-Oxide-Semiconductor Field Effect Transistor) memory device, two dimensional numerical computer simulation program was developed. The equation discretization was performed by the Finite difference method and the solution was derived by the Iteration method. The doping profile of n-channel device which was fabricated by 1Mbit CMOS process was observed. The electrical potential and the carrier concentration distribution to applied bias condition were observed in the inner of a device. As a result of the write and the erase to memory charge quantity, the threshold voltage shift is expected. Therefore, without device fabrication, the operating characteristics of the device was observed under various the processing and the operating condition.

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