Simeon Gilbert

Sandia National Laboratories

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P. A. Dowben

University of Nebraska–Lincoln

Michael P. Siegal

Sandia National Laboratories

Alexander Sinitskii

University of Nebraska–Lincoln

Alexey Lipatov

South Dakota School of Mines and Technology

Laura Biedermann

Sandia National Laboratories

Peter Anand Sharma

Sandia National Laboratories

Andrew J. Yost

Oklahoma State University

Takashi Komesu

University of Nebraska–Lincoln

Paul G. Kotula

Sandia National Laboratories

M. C. Asensio

Instituto de Ciencia de Materiales de Madrid

Cooperative Institutions

University of Nebraska–Lincoln

Sandia National Laboratories

Sandia National Laboratories California

South Dakota State University

University at Buffalo, State University of New York

University of Northern Iowa

Indian Institute of Technology Mandi

Arizona State University

University of North Texas

University of Illinois Urbana-Champaign

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Fluorescent detection of cholesterol using p-Sulfonatocalix[4]arene functionalized carbon nanotubes and thermally reduced graphite oxide composites

Chemical Physics Letters (2019)

Krishna Aryal Thilini K. Ekanayaka Simeon Gilbert P. A. Dowben Hae Kyung Jeong

Rhodamine 6G

Graphite oxide

Rhodamine B

10.1016/j.cplett.2019.136856

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Citations (7)

Granular metals with SiN _x dielectrics

Nanotechnology (2023)

Simeon Gilbert Melissa Meyerson Paul G. Kotula Samantha G. Rosenberg Thomas Kmieciak

Abstract Understanding and controlling nanoscale interface phenomena, such as band bending and secondary phase formation, is crucial for electronic device optimization. In granular metal (GM) studies, where metal nanoparticles are embedded in an insulating matrix, the importance of interface phenomena is frequently neglected. We demonstrate that GMs can serve as an exemplar system for evaluating the role of secondary phases at interfaces through a combination of x-ray photoemission spectroscopy (XPS) and electrical transport studies. We investigated SiN x as an alternative to more commonly used oxide-insulators, as SiN x -based GMs may enable high temperature applications when paired with refractory metals. Comparing Co-SiN x and Mo-SiN x GMs, we found that, in the tunneling-dominated insulating regime, Mo-SiN x had reduced metal-silicide formation and orders-of-magnitude lower conductivity. XPS measurements indicate that metal-silicide and metal-nitride formation are mitigatable concerns in Mo-SiN x . Given the metal-oxide formation seen in other GMs, SiN x is an appealing alternative for metals that readily oxidize. Furthermore, SiN x provides a path to metal-nitride nanostructures, potentially useful for various applications in plasmonics, optics, and sensing.

10.1088/1361-6528/ace4d2

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Citations (2)

Controlling Interface Interactions in Granular Metal Thin Films.

Simeon Gilbert Melissa Meyerson Samantha G. Rosenberg Paul G. Kotula Nathan Madden

Interface (matter)

10.2172/2005720

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The effect of metal–insulator interface interactions on electrical transport in granular metals

Journal of Physics Condensed Matter (2022)

Simeon Gilbert Samantha G. Rosenberg Paul G. Kotula Thomas Kmieciak Laura Biedermann

We present an in-depth study of metal-insulator interfaces within granular metal (GM) films and correlate their interfacial interactions with structural and electrical transport properties. Nominally 100 nm thick GM films of Co and Mo dispersed within yttria-stabilized zirconia (YSZ), with volumetric metal fractions (φ) from 0.2-0.8, were grown by radio frequency co-sputtering from individual metal and YSZ targets. Scanning transmission electron microscopy and DC transport measurements find that the resulting metal islands are well-defined with 1.7-2.6 nm average diameters and percolation thresholds betweenφ= 0.4-0.5. The room temperature conductivities for theφ= 0.2 samples are several orders of magnitude larger than previously-reported for GMs. X-ray photoemission spectroscopy indicates both oxygen vacancy formation within the YSZ and band-bending at metal-insulator interfaces. The higher-than-predicted conductivity is largely attributed to these interface interactions. In agreement with recent theory, interactions that reduce the change in conductivity across the metal-insulator interface are seen to prevent sharp conductivity drops when the metal concentration decreases below the percolation threshold. These interface interactions help interpret the broad range of conductivities reported throughout the literature and can be used to tune the conductivities of future GMs.

Percolation (cognitive psychology)

10.1088/1361-648x/ac5706

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Citations (3)

Corrigendum: Surface termination and Schottky-barrier formation of In₄Se₃(001) (2020 Semicond. Sci. Technol. 35 065009)

Semiconductor Science and Technology (2021)

Archit Dhingra P. V. Galiy Lu Wang Nataliia S. Vorobeva Alexey Lipatov

10.1088/1361-6641/abf9e7

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Development of spin-gapless semiconductivity and half metallicity in Ti$_{\mathrm{2}}$MnAl by substitutions for Al

Bulletin of the American Physical Society (2016)

Pavel Lukashev Simeon Gilbert B. Staten Noah Hurley R. Fuglsby

Gapless playback

Source

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Structural disorder and magnetism in the spin-gapless semiconductor CoFeCrAl

AIP Advances (2016)

R. N. P. Choudhary Parashu Kharel Shah Valloppilly Yunlong Jin Andrew O’Connell

Disordered CoFeCrAl and CoFeCrSi0.5Al0.5 alloys have been investigated experimentally and by first-principle calculations. The melt-spun and annealed samples all exhibit Heusler-type superlattice peaks, but the peak intensities indicate a substantial degree of B2-type chemical disorder. Si substitution reduces the degree of this disorder. Our theoretical analysis also considers several types of antisite disorder (Fe-Co, Fe-Cr, Co-Cr) in Y-ordered CoFeCrAl and partial substitution of Si for Al. The substitution transforms the spin-gapless semiconductor CoFeCrAl into a half-metallic ferrimagnet and increases the half-metallic band gap by 0.12 eV. Compared CoFeCrAl, the moment of CoFeCrSi0.5Al0.5 is predicted to increase from 2.01 μB to 2.50 μB per formula unit, in good agreement with experiment.

Magnetism

Ferrimagnetism

Gapless playback

Half-metal

10.1063/1.4943306

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Citations (33)

Strong Metal–Sulfur Hybridization in the Conduction Band of the Quasi-One-Dimensional Transition-Metal Trichalcogenides: TiS₃ and ZrS₃

The Journal of Physical Chemistry C (2022)

Simeon Gilbert Hemian Yi Tula R. Paudel Alexey Lipatov Andrew J. Yost

The elemental contributions to the conduction bands of the transition-metal trichalcogenides TiS3 and ZrS3 were examined using X-ray absorption spectroscopy, at the Ti and S 2p edges and the Zr 3p edges. A comparative study of these two compounds shows that the bottom of the conduction band, for both TiS3 and ZrS3, is comprised mainly of hybridized transition metal–sulfur orbitals, either Ti 3d and S 3p orbitals or Zr 4d and S 3p orbitals. Density functional theory and experiment both indicate that the bottom of the conduction band, in the case of TiS3, has the Ti 3d weight. Although weak, experiment indicates that the S-weighted contribution to the conduction band minimum for ZrS3 is greater than in the case of TiS3. For ZrS3, theory, however, indicates that the conduction band is dominated by hybridization of the Zr 4d and S 3p orbitals, including in the vicinity of the bottom of the conduction band.

Metal L-edge

10.1021/acs.jpcc.2c05589

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Citations (11)

IMPEDANCE CHARACTERISTICS OF MO-SINX GRANULAR METALS.

Michael P. McGarry Simeon Gilbert Peter Anand Sharma William Bachman Jack Flicker

10.2172/2005531

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Band Bending at the Gold (Au)/Boron Carbide-Based Semiconductor Interface

Zeitschrift für Physikalische Chemie (2018)

Elena Echeverría George Peterson Bin Dong Simeon Gilbert Adeola Oyelade

Abstract We have used X-ray photoemission spectroscopy to study the interaction of gold (Au) with novel boron carbide-based semiconductors grown by plasma-enhanced chemical vapor deposition (PECVD). Both n- and p-type films have been investigated and the PECVD boron carbides are compared to those containing aromatic compounds. In the case of the p-type semiconducting PECVD hydrogenated boron carbide samples, the binding energy of the B(1s) core level shows a shift to higher binding energies as the Au is deposited, an indication of band bending and possibly Schottky barrier formation. In the case of the n-type boron carbide semiconductors the interaction at the interface is more typical of an ohmic contact. Addition of the aromatic compounds increases the change in binding energies on both n-type and p-type PECVD boron carbide semiconductors, and the gold appears to diffuse into the PECVD boron carbides alloyed with aromatic moieties.

Boron carbide

Band bending

Ohmic contact

10.1515/zpch-2017-1038

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Citations (5)