• Title/Summary/Keyword: magnetic semiconductor

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Macro-Model of Magnetic Tunnel Junction for STT-MRAM including Dynamic Behavior

  • Kim, Kyungmin;Yoo, Changsik
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.14 no.6
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    • pp.728-732
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    • 2014
  • Macro-model of magnetic tunnel junction (MTJ) for spin transfer torque magnetic random access memory (STT-MRAM) has been developed. The macro-model can describe the dynamic behavior such as the state change of MTJ as a function of the pulse width of driving current and voltage. The statistical behavior has been included in the model to represent the variation of the MTJ characteristic due to process variation. The macro-model has been developed in Verilog-A.

Anisotropy Coupling in Patterned Thin Films with Mixed Uniaxial Anisotropies

  • Nam, Yoon Jae;Lee, Tae Young;Lim, Sang Ho
    • Journal of Magnetics
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    • v.19 no.3
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    • pp.232-236
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    • 2014
  • Anisotropy coupling in thin films with mixed induced and shape anisotropies is investigated. A 200-nm-thick Co-Fe-Pd-B thin film with a large induced anisotropy of 57 Oe is fabricated and then patterned into micron-sized cells to provide shape anisotropy, whose strength has a similar magnitude to that of the induced anisotropy for enhancing the anisotropy coupling. The angles between the two mixed anisotropies considered are $0^{\circ}$, $90^{\circ}$, and $110^{\circ}$. Hysteresis loops measured under in-plane magnetic fields along various directions indicate no anisotropy coupling behaviour for all the three angles examined in this study.

Superconducting Junctions of InAs Semiconductor Nanowires

  • Doh, Yong-Joo;Franceschi, Silvano De;van Dam, Jorden A.;Bakkers, Erik P. A. M.;Kouwenhoven, Leo P.
    • Progress in Superconductivity
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    • v.9 no.2
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    • pp.136-139
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    • 2008
  • InAs semiconductor nanowires can provide a promising platform to integrate superconducting quantum circuit, which exploits tunable supercurrent under the operation of gate voltage. We report temperature and magnetic field dependence of the nanowire superconducting junctions, which is in agreement with the proximity-effect theory of superconductor-normal metal-superconductor weak link. Superconducting coherence length of the InAs nanowire is estimated from the fit and magnetic-field dependence of the critical current and the subgap structure of dI/dV is discussed as well.

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Magnetic Effects of La0.67Sr0.33MnO3 on W-C-N Diffusion Barrier Thin Films

  • Song, Moon-Kyoo;So, Ji-Seop;Shim, In-Bo;Lee, Chang-Woo
    • Journal of the Korean Magnetics Society
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    • v.15 no.2
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    • pp.133-136
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    • 2005
  • In the case of contacts between semiconductor and metal in semiconductor devices, they tend to be unstable because of thermal budget. To prevent these problems we deposited W-C-N diffusion barrier for preventing the interdiffusion between metal and semiconductor. The thickness of the barrier is $1,000{\AA}$ and the pressure is 3 mTorr during the deposition. In this work we coated LSMO (CMR material) on W-C-N diffusion barrier and then we studied the interface effects between LSMO layer and W-C-N diffusion barrier. We got results that the magnetic characteristics of LSMO thin film are still maintained after annealing at $800^{\circ}C$ for 3 hr because W-C-N thin diffusion barrier was prevented the diffusion of oxygen between LSMO and Si substrate.

A study on the dynamic characteristics of exciting Flexural beam by ultrasonic wave (초음파에 의해서 가진되어지는 Flexural Beam의 동특성에 관한 연구)

  • Jeong, Sang-Hwa;Shin, Sang-Moon;Kim, Gwang-Ho;Lee, Sang-Hee;Kim, Ju-Hwan
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.792-796
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    • 2006
  • In recent years, the semiconductor industry and the optical industry is developed rapidly. The recent demand has expanded for optical components such as a optical lens, a optical semiconductor and a measuring instrument. Object transport systems are driven typically by the magnetic field and the conveyer belt. Recent industry requires more faster and efficient transport system. However, conventional transport systems are not adequate for transportation of optical elements and semiconductors. Because conveyor belts can damage precision optical elements by the contact force and magnetic systems can destroy the inner structure of semiconductor by the magnetic field. In this paper, the levitation transport system using ultrasonic wave is developed for transporting precision elements without damages. This transport system is using 2-mode ultrasonic wave excitation and flexural beam modes shapes are evaluated. It compared simulation results with experimental results

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Review of Hazardous Agent Level in Wafer Fabrication Operation Focusing on Exposure to Chemicals and Radiation (반도체 산업의 웨이퍼 가공 공정 유해인자 고찰과 활용 - 화학물질과 방사선 노출을 중심으로 -)

  • Park, Donguk
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.26 no.1
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    • pp.1-10
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    • 2016
  • Objectives: The aim of this study is to review the results of exposure to chemicals and to extremely low frequency(ELF) magnetic fields generated in wafer fabrication operations in the semiconductor industry. Methods: Exposure assessment studies of silicon wafer fab operations in the semiconductor industry were collected through an extensive literature review of articles reported until the end of 2015. The key words used in the literature search were "semiconductor industry", "wafer fab", "silicon wafer", and "clean room," both singly and in combination. Literature reporting on airborne chemicals and extremely low frequency(ELF) magnetic fields were collected and reviewed. Results and Conclusions: Major airborne hazardous agents assessed were several organic solvents and ethylene glycol ethers from Photolithography, arsenic from ion implantation and extremely low frequency magnetic fields from the overall fabrication processes. Most exposures to chemicals reported were found to be far below permissible exposure limits(PEL) (10% < PEL). Most of these results were from operators who handled processes in a well-controlled environment. In conclusion, we found a lack of results on exposure to hazardous agents, including chemicals and radiation, which are insufficient for use in the estimation of past exposure. The results we reviewed should be applied with great caution to associate chronic health effects.

Microstructure and Magnetic properties of $Ti_{1-x}Co_xO_2$ Magnetic semiconductor thin films by Metal Organic Chemical Vapor Deposition (유기금속화학기상증착법으로 제조된 자성반도체 $Ti_{1-x}Co_xO_2$ 박막의 미세구조 및 자기적 특성)

  • Seong, Nak-Jin;Yoon, Soon-Gil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07a
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    • pp.155-159
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    • 2003
  • Polycrystalline $Ti_{1-x}Co_xO_2$ thin films on $SiO_2$ (200 nm)/Si (100) substrates were prepared using liquid-delivery metalorganic chemical vapor deposition. Microstructures and ferromagnetic properties were investigated as a function of doped Co concentration. Ferromagnetic behaviors of polycrystalline films were observed at room temperature, and the magnetic and structural properties strongly depended on the Co distribution, which varied widely with doped Co concentration. The annealed $Ti_{1-x}Co_xO_2$ thin films with $x{\leq}0.05$ showed a homogeneous structure without any clusters, and pure ferromagnetic properties of thin films are only attributed to the $Ti_{1-x}Co_xO_2$ (TCO) phases. On the other hand, in case of thin films above x=0.05, Co clusters formed in a homogeneous $Ti_{1-x}Co_xO_2$ Phase, and the overall ferromagnetic (FM) properties depended on both $FM_{TCO}$ and $FM_{Co}$. Co clusters with about 10nm-150nm size decreased the value of Mr (the remanent magnetization) and increased the saturation magnetic field.

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Structural, Optical, and Magnetic Properties of Si1-xMnxTe1.5 Single Crystals (Si1-xMnxTe1.5 단결정의 구조적, 광학적, 자기적 특성에 관한 연구)

  • Hwang, Young-Hun;Um, Young-Ho;Cho, Sung-Lae
    • Journal of the Korean Magnetics Society
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    • v.16 no.3
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    • pp.178-181
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    • 2006
  • We have investigated the Mn concentration-dependent structural, optical, magnetic properties in IV-VI diluted magnetic semiconductor $Si_{1-x}Mn_xTe_{1.5} $ crystals prepared by the vertical Bridgman technique. X-ray studies showed the single crystalline hexagonal crystal structure. From the optical absorption measurements energy band gap were found to decreases with increasing x and temperature. From the magnetization measurements the samples had ferromagnetic ordering with Curie temperature $T_C$ about 80 K. With increasing Mn concentration, the average magnetic moments per Mn atom determined from the saturated magnetization increased.

Semiconductor magnetic field sensors (화합물 반도체 자기센서)

  • 차준호;김남영
    • Electrical & Electronic Materials
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    • v.9 no.5
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    • pp.512-517
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    • 1996
  • 본 고는 반도체 재료가 갖는 자기효과를 이용하여 자기센서의 종류 및 특성등에 대하여 서술하였다. 반도체 LSI의 응용분야가 확대됨에 따라서 반도체 센서를 이용한 극소형화, 고성능화, 저가격화, 다기능화등이 가능하게 되었다. 이러한 상황에서 반도체를 이용한 홀 소자나 자기저항 소자와 같은 자기센서 등을 주변회로와 일체화시킨 초소형 시스템에 대한 연구가 활발하다. 특히 화합물 반도체는 자기센서에 적합한 물리적인 특성을 갖고 있기 때문에, 자기센서로 효율을 나타내고 있다. 반도체의 미세가공기술의 발전과 LSI제조기술의 발전을 이용하여 센서의 집적화, 저가격화를 가능하게 하였으며, 다른 종류의 반도체 센서들을 자기센서와 함께 하나의 칩위에 장착할 수 있는 응용집적센서(Application-specific Integrated Sensor)가 더욱 중요한 역할을 할 것이다.

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An Experimental Analysis on the Thermal Plasma Characteristics to the Geometry in Non-Transferred Torch (비이송식 플라즈마 토치 구조에 따른 열 플라즈마 특성 시험)

  • Jeong, An-Mok;Jun, Euy-Sik
    • Journal of the Semiconductor & Display Technology
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    • v.8 no.4
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    • pp.89-94
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    • 2009
  • The influence on a stability of thermal plasma has been investigated in an electrode structure of non-transferred plasma torch. The variations of dynamic characteristic of the arc voltage was analyzed and compared in terms of voltage character and nozzle types for both the step-shaped nozzles and magnetic-approved cylindrical nozzle. From the experimental results, an electrode gap, flow rate of arc gas, and currents are considered as major operational parameters. As conclusion, it was assured that a torch with step-shaped nozzles of magnetic-approved type produce the stable plasma jet.

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