• Title/Summary/Keyword: Thermal Hysteresis

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Characterization of $Nb/Al-Al_2O_3/Nb$ Josephson junction arrays fabricated With and Without cooling substrate (기판 냉각과 비냉각으로 제작된 $Nb/Al-Al_2O_3/Nb$ 조셉슨 접합 어레이의 특성)

  • Hong, Hyun-Kwon;Kim, Kyu-Tae;Park, Se-Il;Lee, Kie-Young
    • Proceedings of the KIEE Conference
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    • 2001.07c
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    • pp.1402-1404
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    • 2001
  • Josephson junction arrays of the type $Nb/Al-Al_2O_3/Nb$ were prepared by DC magnetron sputtering. The tunnel barrier was formed by in-situ thermal oxidation. Individual junctions were defined using selective niobium etching process(SNEP). The characteristic curves of Josephson junction arrays fabricated with and without cooling the substrate were represented. The junctions deposited without cooling showed poor characteristics(high leakage current, low gap voltage), and a high quality Josephson junction array of 2,000 junctions with high hysteresis was obtained with cooling and when operated at 74.6 GHz, it generated stable quantized voltage steps up to 2.2 V.

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Magnetically Soft Nanomaterials Obtained by Devitrification of Metallic Glasses

  • Kulik, Tadeusz;Ferenc, Jaroslaw;Kowalczyk, Maciej;Xiubing, Liang;Nedelko, Natalya
    • Journal of Magnetics
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    • v.9 no.2
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    • pp.65-68
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    • 2004
  • Magnetically soft nanomaterials obtained by controlled crystallisation of metallic glasses are the newest group of materials for inductive components. In particular, research is carried out in the field of alloys for high temperature applications. This kind of materials must meet two basic requirements: good magnetic properties and stability of properties and structure. In the present work the magnetic properties and structure of Fe-Co-Hf-Zr-Cu-B (HIDTPERM-type) alloys were investigated, as well as their stability. Differential thermal analysis, (DTA), X-ray diffractometry (XRD), transmission electron microscopy (TEM), magnetometry (VSM) and quasistatic hysteresis loop recording were used to characterise structure and properties of the alloys investigated. Optimisation against properties and their stability was performed, resulting in formulation of chemical composition of the optimum alloy, as well as its heat treatment.

Microstructure and Magnetic State of Fe3O4-SiO2 Colloidal Particles

  • Kharitonskii, P.V.;Gareev, K.G.;Ionin, S.A.;Ryzhov, V.A.;Bogachev, Yu.V.;Klimenkov, B.D.;Kononova, I.E.;Moshnikov, V.A.
    • Journal of Magnetics
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    • v.20 no.3
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    • pp.221-228
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    • 2015
  • Colloidal particles consisted of individual nanosized magnetite grains on the surface of the silica cores were obtained by two-stage sol-gel technique. Size distribution and microstructure of the particles were analyzed using atomic force microscopy, X-ray diffraction and Nitrogen thermal desorption. Magnetic properties of the particles were studied by the method of the longitudinal nonlinear response. It has been shown that nanoparticles of magnetite have a size corresponding to a superparamagnetic state but exhibit hysteresis properties. The phenomenon was explained using the magnetostatic interaction model based on the hypothesis of iron oxide particles cluster aggregation on the silica surface.

Electrical and Optical Characteristics of X/40/60 PLZT Thin Films by Sol-Gel Processing (Sol-Gel 법에 의한 X/40/60 PLZT 박막의 전기 및 광학 특성)

  • 이진욱;마석범;강종윤;장낙원;박정흠
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1996.11a
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    • pp.139-142
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    • 1996
  • X/40/60 PLZT thin films were prepared by sol-gel processing and annealed by rapid thermal annealing(RTA). X/40/60 PLZT thin films were crystallized at 75$0^{\circ}C$ for 5min by RTA. Hysteresis curves were narrowed and coercive field was decreased from 50kV/cm to 31.2 kV/cm and remnant polarization was also decreased from 14.3$\mu$C/$\textrm{cm}^2$ to 6.72$\mu$C/$\textrm{cm}^2$ as La mol% increased. Dielectric constanat and optical transmittance were increased with increasing La mol%.

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X-ray and Plasma Process Induced Damages to PLZT Capacitor Characteristics for DRAM Applications

  • Kim, Jiyoung
    • The Korean Journal of Ceramics
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    • v.3 no.3
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    • pp.213-217
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    • 1997
  • In this paper, the imparct of X-ray and plasma process-induced-damages to La doped Lead Zirconate Titanate (PLZT, (Pb1-xLa)(Zr0.5Ti0.5)O3) capacitor characteristics have been investigated from the viewpoint of gigabit scale dynamic random access memory (DRAM) applications. Plamsa damage causes asymmetric degradation on hysteresis characteristics of PLZT films. On the other hand, X-ray damage results in a symmetrical reduction of charge storage densities (Qc's) for both polarities. As La concentration increases in the films, the radiation hardness of PLZT films on X-ray and plasma exposures is improved. It is observed that the damaged devices are fully recovered by thermal annealing under oxygen ambient.

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Thermally/Dynamically Stable Superhydrophobic ZnO Nanoparticles on Various Substrates

  • Lee, M.K.;Kwak, G.J.;Yong, K.J.
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.08a
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    • pp.360-360
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    • 2011
  • We demonstrated the fabrication method of superhydrophobic nanocoating through a facile spin-coating and the chemical modification. The resulting coating showed a tremendous water repellency with a static water contact angle (CA) of 158$^{\circ}$ and a hysteresis of 1$^{\circ}$. The number of ZnO nanoparticle (NP) coating cycles affected on the surface roughness, which is key role for superhydrophobic surface, and thus the CA can be modulated by changing the ZnO NP coating cycles. The CA can be controlled by changing the carbon length of Self-Assembled Monolayers(SAM). This simple ZnO coating is substrate-independent including flexible surfaces, papers and cotton fabrics, which can effectively be used in various potential applications. We also observed the thermal and dynamic stabilities of SAM on ZnO nanoparticles. The superhydrophobicic surface maintained its superhydrophobic properties below 250$^{\circ}C$ and under dynamic conditions.

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Organic Thin Film Transistors with Cross-linked PVP Gate Dielectrics by Using Photo-initiator and PMF

  • Yun, Ho-Jin;Baek, Kyu-Ha;Park, Kun-Sik;Shin, Hong-Sik;Ham, Yong-Hyun;Lee, Ga-Won;Lee, Ki-Jun;Wang, Jin-Suk;Do, Lee-Mi
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.312-314
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    • 2009
  • We have fabricated pentacene based organic thin film transistors (OTFTs) with formulated poly[4-vinylphenol] (PVP) gate dielectrics. The gate dielectrics is composed of PVP, poly[melamine-coformaldehyde] (PMF) and photo-initiator [1-phenyl-2-hydroxy-2-methylpropane-1-one, Darocur1173]. By adding small amount (1 %) of photo-initiator, the cross-linking temperature is lowered to $115^{\circ}C$, which is lower than general thermal curing reaction temperature of cross-linked PVP (> $180^{\circ}C$). The hysteresis and the leakage current of the OTFTs are also decreased by adding the PMF and the photoinitiator in PVP gate dielectrics.

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High Quality Ultrathin Gate Oxides Grown by Low-Temperature Radical Induced Oxidation for High Performance SiGe Heterostructure CMOS Applications (저온 래디컬 산화법에 의한 고품질 초박막 게이트 산화막의 성장과 이를 이용한 고성능 실리콘-게르마늄 이종구조 CMOS의 제작)

  • 송영주;김상훈;이내응;강진영;심규환
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.9
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    • pp.765-770
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    • 2003
  • We have developed a low-temperature, and low-pressure radical induced oxidation (RIO) technology, so that high-quality ultrathin silicon dioxide layers have been effectively produced with a high reproducibility, and successfully employed to realize high performace SiGe heterostructure complementary MOSFETs (HCMOS) lot the first time. The obtained oxide layer showed comparable leakage and breakdown properties to conventional furnace gate oxides, and no hysteresis was observed during high-frequency capacitance-voltage characterization. Strained SiGe HCMOS transistors with a 2.5 nm-thick gate oxide layer grown by this method exhibited excellent device properties. These suggest that the present technique is particularly suitable for HCMOS devices requiring a fast and high-precision gate oxidation process with a low thermal budget.

Characteristics of PZT thin film on the g1ass substrate (유리 기판 위에서의 PZT 박막의 특성에 관한 연구)

  • Ju, Pil-Yeon;Jeong, Kyu-Won;Park, Young;Park, Ki-Yeop;Song, Joon-Tae
    • Proceedings of the KIEE Conference
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    • 2000.07c
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    • pp.1477-1479
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    • 2000
  • The annealing treatments on rf magnetron sputtered PZT($Pb_{1.05}(Zr_{0.52},Ti_{0.48})O_3$) thin films(4000${\AA}$) have been investigated for a structure of PZT/Pt/Ti/ITO coated glass. Crystallization properties of PZT films were strongly dependent on RTA(Rapid Thermal Annealing) annealing temperature and time. We were able to obtain a perovskite structure of PZT at 650$^{\circ}C$ and 10min. P-E curves of Pd/PZT/Pt capacitor demonstrate typical hysteresis loops. The measured values of $P_r$, $E_c$ were 15.8[${\mu}C/cm^2$], 95[kV/cm] respectively. Polarization value decrease about 10% after $10^9$ cycles.

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The Influence of Thermal Annealing on Magnetostatic Properties of thin Ni Films

  • Shalyguina, E.E.;Kim, Chong-Oh;Kim, Cheol-Gi;Seo, Jung-Hwa
    • Journal of Magnetics
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    • v.8 no.4
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    • pp.133-137
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    • 2003
  • The magnetostatic properties of the as-deposited and annealed at T=300 and 400$^{\circ}C$ Ni films were investigated employing both magneto-optical magnetometer and VSM. The Ni films of 50∼200 nm thicknesses were prepared by DC magnetron sputtering technique. The strong influence of annealing temperature on magnetostatic properties of the studied samples was discovered. For the annealed Ni films, the increase of the coercivity H$_c$ (up to 4 times) in comparison with that of as-deposited samples was revealed. The obtained results were explained by using crystallographic structural data of the samples.