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Band offsets of La2O3 on (0001) GaN grown by reactive molecular-beam epitaxy

Applied Physics Letters

Ihlefeld, Jon F.; Brumbach, Michael T.; Atcitty, Stanley

La2O3 films were prepared on (0001)-oriented GaN substrates via reactive molecular-beam epitaxy. Film orientation and phase were assessed using reflection high-energy electron and X-ray diffraction. Films were observed to grow as predominantly hexagonal La2O3 for thicknesses less than 10 nm while film thickness greater than 10 nm favored mixed cubic and hexagonal symmetries. Band offsets were characterized by X-ray photoelectron spectroscopy on hexagonally symmetric films and valence band offsets of 0.63 ± 0.04 eV at the La2O3/GaN interface were measured. A conduction band offset of approximately 1.5 eV could be inferred from the measured valence band offset. © 2013 AIP Publishing LLC.

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TYPE Journal Article YEAR 2013
DOIOSTIScopus

Realization of Tellurium-based all dielectric optical metamaterials using a multi-cycle deposition-etch process

2013 Conference on Lasers and Electro-Optics, CLEO 2013

Ihlefeld, Jon F.; Dominguez, Jason; Bower, John E.; Burckel, David B.; Sinclair, Michael B.; Brener, Igal

Tellurium dielectric resonator metamaterials were fabricated using a newly developed multi-cycle deposition-etch process. Deposition and etching of Tellurium were studied in detail. All the samples showed two transmission minima corresponding to magnetic and electric dipole resonances. © 2013 The Optical Society.

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TYPE Conference YEAR 2013
OSTIScopus

A Summary of the Theory and Design Team Efforts for the Sandia Metamaterials Science and Technology Grand Challenge LDRD

Basilio, Lorena I.; Brener, Igal; Burckel, David B.; Shaner, Eric A.; Wendt, Joel R.; Luk, Ting S.; Ellis, A.R.; Bender, Daniel A.; Clem, Paul; Rasberry, Roger D.; Langston, William L.; Ihlefeld, Jon F.; Dirk, Shawn M.; Warne, Larry K.; Peters, David; El-Kady, Ihab F.; Reinke, Charles M.; Loui, Hung; Williams, Jeffery T.; Sinclair, Michael B.; Mccormick, Frederick B.

Abstract not provided.

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TYPE Presentation YEAR 2012
OSTI

An automated electrochemical probe for evaluation of thin films

Journal of the Electrochemical Society

Small, Leo; Cook, Adam; Apblett, Christopher A.; Ihlefeld, Jon F.; Brennecka, Geoff; Duquette, David

An electrochemical probe station (EPS) for automated electrochemical testing of electronic-grade thin films is presented. Similar in design to a scanning droplet cell, this modular system features a flexible probe tip capable of contacting both metallic and oxide surfaces. Using the highly sensitive Pt-H 2SO 4 system, it is demonstrated that the EPS obtains results equivalent to those of a traditional electrochemical cell. Further, electrical testing of thin film PbZr 0.52Ti 0.48O 3 shows that this system may be used to ascertain fundamental electrical properties of dielectric films. © 2012 The Electrochemical Society.

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TYPE Journal Article YEAR 2012
ScopusOSTI

Fast lithium-ion conducting thin-film electrolytes integrated directly on flexible substrates for high-power solid-state batteries

Advanced Materials

Ihlefeld, Jon F.; Clem, Paul; Doyle, B.L.; Kotula, Paul G.; Fenton, Kyle R.; Apblett, Christopher A.

By utilizing an equilibrium processing strategy that enables co-firing of oxides and base metals, a means to integrate the lithium-stable fast lithium-ion conductor lanthanum lithium tantalate directly with a thin copper foil current collector appropriate for a solid-state battery is presented. This resulting thin-film electrolyte possesses a room temperature lithium-ion conductivity of 1.5 × 10 -5 S cm -1, which has the potential to increase the power of a solid-state battery over current state of the art. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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TYPE Journal Article YEAR 2011
DOIOSTIScopus

Influence of anisotropy on thermal boundary conductance at solid interfaces

Physical Review B - Condensed Matter and Materials Physics

Hopkins, Patrick E.; Beechem, Thomas E.; Duda, John C.; Hattar, Khalid M.; Ihlefeld, Jon F.; Rodriguez, Mark A.; Piekos, Edward S.

We investigate the role of anisotropy on interfacial transport across solid interfaces by measuring the thermal boundary conductance from 100 to 500 K across Al/Si and Al/sapphire interfaces with different substrate orientations. The measured thermal boundary conductances show a dependency on substrate crystallographic orientation in the sapphire samples (trigonal conventional cell) but not in the silicon samples (diamond cubic conventional cell). The change in interface conductance in the sapphire samples is ascribed to anisotropy in the Brillouin zone along the principal directions defining the conventional cell. This leads to resultant phonon velocities in the direction of thermal transport that vary nearly 40% based on crystallographic direction. © 2011 American Physical Society.

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TYPE Journal Article YEAR 2011
DOIOSTIScopus

Reduction in thermal boundary conductance due to proton implantation in silicon and sapphire

Applied Physics Letters

Hopkins, Patrick E.; Hattar, Khalid M.; Beechem, Thomas E.; Ihlefeld, Jon F.; Medlin, Douglas L.; Piekos, Edward S.

We measure the thermal boundary conductance across Al/Si and Al/ Al 2 O3 interfaces that are subjected to varying doses of proton ion implantation with time domain thermoreflectance. The proton irradiation creates a major reduction in the thermal boundary conductance that is much greater than the corresponding decrease in the thermal conductivities of both the Si and Al2 O3 substrates into which the ions were implanted. Specifically, the thermal boundary conductances decrease by over an order of magnitude, indicating that proton irradiation presents a unique method to systematically decrease the thermal boundary conductance at solid interfaces. © 2011 American Institute of Physics.

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TYPE Journal Article YEAR 2011
DOIOSTIScopus

Structure-property relations in negative permittivity reststrahlen materials for IR metamaterial applications

Ihlefeld, Jon F.; Ginn, James C.; Rodriguez, Marko A.; Kotula, Paul G.; Clem, Paul; Sinclair, Michael B.

We will present a study of the structure-property relations in Reststrahlen materials that possess a band of negative permittivities in the infrared. It will be shown that sub-micron defects strongly affect the optical response, resulting in significantly diminished permittivities. This work has implications on the use of ionic materials in IR-metamaterials.

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TYPE Conference YEAR 2010
OSTI
Results 101–200 of 204
Results 101–200 of 204