• 제목/요약/키워드: photoemission

검색결과 220건 처리시간 0.027초

Valence Band Photoemission Study of the Kondo Insulator CeNiSn

  • Kang, J.S.;Olson, C.G.;Ouki, Y.
    • Journal of Magnetics
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    • 제2권4호
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    • pp.111-115
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    • 1997
  • The electronic structure of the Kondo insulator CeNiSn has been investigated by using photoemission spectroscopy. A satellite feature is observed in the valence band spectrum about 6 eV below the Ni 3d main peak, indicating a strong Ni 3d Coulomb correlation in CeNiSn. The Ce 4f partial spectral weight exhibits three peak structures, including one due to the 4f1\longrightarrow4f0 transition, another near EF, and the other which overlaps the Ni 3d main peak. We interpret the peak near EF as reflecting mainly the Ce 4f/Sn 5p hybridization, whereas that around the ni 3d main peak as reflecting both the Ce 4f/Ni 3d and Ce 5d/Ni 3d hybridization. Yield measurements across the 4d\longrightarrow4f threshold indicate the Ce valence to be close to 3+. The prominent Fermi edge suggests a metallic ground state in CeNiSn.

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Accurate Prediction Method of Breakdown Voltage in Air at Atmospheric Pressure

  • Kim, Nam-Kyung;Lee, Se-Hee;Georghiou, G.E.;Kim, Dong-Wook;Kim, Dong-Hun
    • Journal of Electrical Engineering and Technology
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    • 제7권1호
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    • pp.97-102
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    • 2012
  • To predict accurately the breakdown voltage in air at atmospheric pressure, a fully coupled finite element analysis combining the hydrodynamic diffusion-drift equations with Poisson's equation is proposed in the current paper. As three kinds of charged transport particles are nonlinearly coupled with spatial electric fields, the equations should be solved by an iterative numerical scheme, in which secondary effects, such as photoemission and photoionization, are considered. The proposed method has been successfully applied to evaluate the breakdown voltage in circular parallel-plane electrodes. Its validity has been proved through the comparison of the predicted and experimental results. The effects of numerical conditions of the initial charge, photoemission, and background ionization on the discharge phenomena are quantitatively assessed through Taguchi's design of experiment method.

Analysis of materials for protective layers in AC PDPs.

  • Matulevich, Y. T.;Lee, Min-Suk;Kim, Suk-Ki;Choi, Jong-Seo;Zang, Dong-Sik;Kirm, Marco
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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    • pp.213-215
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    • 2007
  • To clarify processes responsible for improved characteristics of protective layers (e.g. SrCaO) the ion-induced electron emission and photoemission from these layers were analyzed. Additionally, a study of ternary Mg-, Ca-, Ba-based compounds as candidate materials for a protective layer of Plasma Display Panels has been performed as well.

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A review on angle resolved photoemission spectroscopy studies of Fe-based superconductors

  • Seo, J.J.;Kim, C.
    • 한국초전도ㆍ저온공학회논문지
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    • 제16권2호
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    • pp.7-19
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    • 2014
  • Since the discovery of iron-based superconductors in 2008, extensive and intensive studies have been performed to find the microscopic theory for the high temperature superconductivity in the materials. Electronic structure is the basic and essential information that is needed for the microscopic theory. Experimentally, angle resolved photoelectron spectroscopy (ARPES) is the most direct tool to obtain the electronic structure information, and therefore has played a vital role in the research. In this review, we review what has been done so far and what is needed to be done in ARPES studies of iron-based superconductors in search of the microscopic theory. This review covers issues on the band structure, orbital order/fluctuation, and gap structure/symmetries as well as some of the theories.

Development of a Photoemission-assisted Plasma-enhanced CVD Process and Its Application to Synthesis of Carbon Thin Films: Diamond, Graphite, Graphene and Diamond-like Carbon

  • Takakuwa, Yuji
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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    • pp.105-105
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    • 2012
  • We have developed a photoemission-assisted plasma-enhanced chemical vapor deposition (PAPE-CVD) [1,2], in which photoelectrons emitting from the substrate surface irradiated with UV light ($h{\nu}$=7.2 eV) from a Xe excimer lamp are utilized as a trigger for generating DC discharge plasma as depicted in Fig. 1. As a result, photoemission-assisted plasma can appear just above the substrate surface with a limited interval between the substrate and the electrode (~10 mm), enabling us to suppress effectively the unintended deposition of soot on the chamber walls, to increase the deposition rate, and to decrease drastically the electric power consumption. In case of the deposition of DLC gate insulator films for the top-gate graphene channel FET, plasma discharge power is reduced down to as low as 0.01W, giving rise to decrease significantly the plasma-induced damage on the graphene channel [3]. In addition, DLC thickness can be precisely controlled in an atomic scale and dielectric constant is also changed from low ${\kappa}$ for the passivation layer to high ${\kappa}$ for the gate insulator. On the other hand, negative electron affinity (NEA) of a hydrogen-terminated diamond surface is attractive and of practical importance for PAPECVD, because the diamond surface under PAPE-CVD with H2-diluted (about 1%) CH4 gas is exposed to a lot of hydrogen radicals and therefore can perform as a high-efficiency electron emitter due to NEA. In fact, we observed a large change of discharge current between with and without hydrogen termination. It is noted that photoelectrons are emitted from the SiO2 (350 nm)/Si interface with 7.2-eV UV light, making it possible to grow few-layer graphene on the thick SiO2 surface with no transition layer of amorphous carbon by means of PAPE-CVD without any metal catalyst.

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