Atomic and electronic structures of barium oxide on Si(0 0 1) studied by metastable impact electron spectroscopy (MIES) and coaxial impact collision ion scattering spectroscopy (CAICISS)

Ikeuchi, T.; Souda, Ryūtarō; Yamamoto, Seiji

doi:10.1016/s0169-4332(02)00224-6

Cited by 5 publications

(3 citation statements)

References 12 publications

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“…It has been previously reported for barium-oxide coated emitters [7] that the barium atoms are released by the chemical reaction between the barium oxide and the substrate, and that these atoms migrate to the surface of the emitter coating by diffusion through the layer of barium oxide. The migration of barium atoms is facilitated by the high operating temperature of the emitter, and also by the porous, microcrystalline structure of the emitter coating [7,8]. This model may explain the difference in the hysteresis of pure barium and barium oxide coatings.…”

Section: Work Function Lowering By Barium Coatingsmentioning

confidence: 99%

Encapsulated Thermionic Energy Converter With Stiffened Suspension

Lee¹,

Bargatin²,

Iwami³

et al. 2012

2012 Solid-State, Actuators, and Microsystems Workshop Technical Digest

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This paper reports a prototype of a mechanically and thermally robust encapsulated microfabricated thermionic energy converter (μ-TEC). We used conformal sidewall deposition of poly-SiC to form stiff suspension legs with U-shaped cross sections, which increase the out-of-plane rigidity and prevent contact with the substrate during the heating of the suspended emitter-a qualitative improvement over the previously reported planar SiC μ-TECs [1]. Furthermore, we tested the new μ-TECs with both barium and barium oxide coatings. The coatings reduced the work function of the SiC emitter to as low as ~2.14 eV and increased the thermionic current by 5-6 orders of magnitude, which is a key step toward realizing a highly efficient thermionic energy converter. In addition, we have sealed small arrays of μ-TECs using an anodically bonded pyrex wafer.

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Section: Work Function Lowering By Barium Coatingsmentioning

confidence: 99%

Encapsulated Thermionic Energy Converter With Stiffened Suspension

Lee¹,

Bargatin²,

Iwami³

et al. 2012

2012 Solid-State, Actuators, and Microsystems Workshop Technical Digest

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“…In order to gain knowledge on the structural, electronic and catalytic properties of AEMO thin films, the atomic and electronic structure should be investigated. Although, over the last decades, a number of studies have been performed related to BaO overlayers on several surfaces, both from the experimental [16][17][18][19][20][21][22] and the theoretical viewpoint [23][24][25], there are still obscure and controversial points concerning how the oxidation of the alkaline earth metal starts and develops on the surface. Among these points are the unusual negative binding energy shifts (NBESs) of some low core atomic levels (Ba 4d and 5p) after barium oxidation.…”

Section: Introductionmentioning

confidence: 99%

Barium and oxygen interaction on the Ni(110) surface at low coverages studied by soft x-ray photoemission spectroscopy: Ba negative binding energy shifts and their correlation with Auger electron spectroscopy shifts

Vlachos

Kamaratos²,

Foulias³

2006

J. Phys.: Condens. Matter

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In this work, barium and oxygen interaction on the Ni(110) surface is investigated, by means of soft x-ray photoemission spectroscopy (SXPS), mainly at submonolayer and monolayer coverages. The results show that oxygen interacts with barium and the substrate as well forming BaO and NiO respectively. The formation of both oxides is consistent with previous Auger electron spectroscopy (AES) results. The oxidation of barium on the surface induces negative binding energy shifts of the Ba low core atomic levels 4d, 5s and 5p. Both initial and final state effects are shown to be necessary in order to explain these peculiar energy shifts. This interpretation is based on correlating the core level binding energy shifts with previously recorded AES transition line shifts, also taking into account the changes of the work function of the surface. The analysis shows that the extra-atomic relaxation energy decreases on going from metallic Ba to BaO. This implies that the reduction of the free electron screening more than counteracts the increase in relaxation energy due to the polarizable O2− anions.

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“…Also alkaline oxides provide surfaces with low work function (WF) and negative electron affinity [3], as well as modifying the catalytic properties of the substrates [4]. Very recently, it has been shown that a BaO thin film on the Si(100) surface, after annealing at 900 K, exhibits WF as small as 0.5 eV [5]. Moreover, AEM oxides contribute a rich variety of physical properties in magnetism, ferroelectricity, structural transformations, metal-insulator transitions and superconductivity [6].…”

Section: Introductionmentioning

confidence: 99%

Auger electron spectroscopy and work function characterization of oxygen adsorption on Ba-covered Ni(110)

Vlachos¹,

Panagiotides

Foulias

2003

J. Phys.: Condens. Matter

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The adsorption of oxygen on a Ba-covered Ni(110) surface has been investigated mainly by Auger electron spectroscopy (AES) and work function (WF) measurements. Low energy AES lines indicate that O interacts with Ba and Ni as well. Both Ba-O and Ni-O interactions take place simultaneously on the surface, progressively leading to BaO and NiO formation. Ba enhances the oxidation of the substrate due to the higher sticking coefficient of O on the Ba/Ni surface. The oxygen interacts with the nickel substrate even at high adsorbate coverage, incorporating under the Ba layer. A part of the Ba adatoms remains non-oxidized even at a high O exposure.

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Atomic and electronic structures of barium oxide on Si(0 0 1) studied by metastable impact electron spectroscopy (MIES) and coaxial impact collision ion scattering spectroscopy (CAICISS)

Cited by 5 publications

References 12 publications

Encapsulated Thermionic Energy Converter With Stiffened Suspension

Encapsulated Thermionic Energy Converter With Stiffened Suspension

Barium and oxygen interaction on the Ni(110) surface at low coverages studied by soft x-ray photoemission spectroscopy: Ba negative binding energy shifts and their correlation with Auger electron spectroscopy shifts

Auger electron spectroscopy and work function characterization of oxygen adsorption on Ba-covered Ni(110)

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