Pseudogap formation in the metallic state of La0.7Sr0.3MnO3 thin films

ABSTRACTVO2 is one of the very few natural materials that can be used to modulate terahertz (THz) radiations. A 100-nm thick VO2, when in its metallic phase, has a charge density of more than ∼ 1015 cm-2 which will strongly reflect and absorb the THz radiation; while in its insulator state, the charge density is lowered by several orders of magnitude to be THz transparent. Therefore, exploiting the metal-insulator transition of VO2 is a potential approach to modulate or even switch THz radiation for THz optics. Here we report that VO2 epitaxial thin films on sapphire substrate exhibits 85% amplitude modulation depth in a broad bandwidth, while this value can be improved to 95% when VO2 film is coated on both sides of a substrate. We further demonstrate that with wafer bonding, 4-layered VO2 thin films exhibit a transmittance as low as -20 dB to -30 dB at their metallic state, enough for switching applications. We also report our proof-of-concept demonstration of THz spatial light modulator that exhibits amplitude modulation as large as 96%, -30 dB pixel-to-pixel crosstalk, and a broad THz bandwidth.

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Switchable Piezoresistive SmS Thin Films on Large Area

Sensors ◽

10.3390/s19204390 ◽

2019 ◽

Vol 19 (20) ◽

pp. 4390 ◽

Cited By ~ 1

Author(s):

Andreas Sousanis ◽

Dirk Poelman ◽

Christophe Detavernier ◽

Philippe F. Smet

Keyword(s):

Thin Films ◽

Photoelectron Spectroscopy ◽

Metallic State ◽

Large Area ◽

Thermally Induced ◽

X Ray ◽

Piezoresistive Sensors ◽

Deposition Parameters ◽

Structural And Electrical Properties ◽

Samarium Monosulfide

Samarium monosulfide (SmS) is a switchable material, showing a pressure-induced semiconductor to metal transition. As such, it can be used in different applications such as piezoresistive sensors and memory devices. In this work, we present how e-beam sublimation of samarium metal in a reactive atmosphere can be used for the deposition of semiconducting SmS thin films on 150 mm diameter silicon wafers. The deposition parameters influencing the composition and properties of the thin films are evaluated, such as the deposition rate of Sm metal, the substrate temperature and the H2S partial pressure. We then present the changes in the optical, structural and electrical properties of this compound after the pressure-induced switching to the metallic state. The back-switching and stability of SmS thin films are studied as a function of temperature and atmosphere via in-situ X-ray diffraction. The thermally induced back switching initiates at 250 °C, while above 500 °C, Sm2O2S is formed. Lastly, we explore the possibility to determine the valence state of the samarium ions by means of X-ray photoelectron spectroscopy.

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Structural and optical properties of MgyNi1–yHx gradient thin films in relation to the as-deposited metallic state

International Journal of Hydrogen Energy ◽

10.1016/j.ijhydene.2009.08.051 ◽

2009 ◽

Vol 34 (21) ◽

pp. 8951-8957 ◽

Cited By ~ 19

Author(s):

R. Gremaud ◽

J.L.M. van Mechelen ◽

H. Schreuders ◽

M. Slaman ◽

B. Dam ◽

...

Keyword(s):

Thin Films ◽

Optical Properties ◽

Metallic State ◽

Structural And Optical Properties

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Sensitivity of the superconducting state in thin films

Science Advances ◽

10.1126/sciadv.aau3826 ◽

2019 ◽

Vol 5 (3) ◽

pp. eaau3826 ◽

Cited By ~ 25

Author(s):

I. Tamir ◽

A. Benyamini ◽

E. J. Telford ◽

F. Gorniaczyk ◽

A. Doron ◽

...

Keyword(s):

Thin Film ◽

Thin Films ◽

Low Temperatures ◽

Superconducting Films ◽

Theoretical Explanation ◽

Two Dimensions ◽

Metallic State ◽

External Radiation ◽

External Perturbations ◽

Extreme Sensitivity

For more than two decades, there have been reports on an unexpected metallic state separating the established superconducting and insulating phases of thin-film superconductors. To date, no theoretical explanation has been able to fully capture the existence of such a state for the large variety of superconductors exhibiting it. Here, we show that for two very different thin-film superconductors, amorphous indium oxide and a single crystal of 2H-NbSe2, this metallic state can be eliminated by adequately filtering external radiation. Our results show that the appearance of temperature-independent, metallic-like transport at low temperatures is sufficiently described by the extreme sensitivity of these superconducting films to external perturbations. We relate this sensitivity to the theoretical observation that, in two dimensions, superconductivity is only marginally stable.

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Surface metallic state of aluminum-nitride (AlN) thin films prepared by direct current (DC)-reactive magnetron sputtering: optical spectroscopic analysis with incoherent light

Scripta Materialia ◽

10.1016/j.scriptamat.2003.11.034 ◽

2004 ◽

Vol 50 (5) ◽

pp. 589-592 ◽

Cited By ~ 9

Author(s):

Nikifor Rakov ◽

Arshad Mahmood ◽

Mufei Xiao

Keyword(s):

Thin Films ◽

Aluminum Nitride ◽

Magnetron Sputtering ◽

Direct Current ◽

Spectroscopic Analysis ◽

Reactive Magnetron Sputtering ◽

Metallic State ◽

Reactive Magnetron ◽

Incoherent Light ◽

Dc Reactive Magnetron Sputtering

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XPS Study of Pt/CexZr1−xO2/Si Composite Systems

MRS Proceedings ◽

10.1557/proc-581-345 ◽

1999 ◽

Vol 581 ◽

Cited By ~ 2

Author(s):

A. Norman ◽

R. Sporken ◽

A. Galtayries ◽

F. Mirabella ◽

K. Keveney ◽

...

Keyword(s):

Thin Films ◽

Mixed Oxides ◽

Incidence Angle ◽

Grazing Incidence ◽

Metallic State ◽

Surface Reduction ◽

Composite Systems ◽

Reducing Conditions ◽

Powder Samples ◽

Xps Study

ABSTRACTThis work describes the study of the surface reduction of ceria zirconia mixed oxides (CeZrO) as either thin films or powders, both with and without Pt present. XPS was used to measure the composition of the surface and the oxidation states of all metals contained within the material. The thin films of CeZrO showed little reactivity towards the reducing conditions used. Grazing incidence angle XRD showed the presence of Ce0.75Zr0.25O2. The thin films prepared with Pt showed that surface reduction of Ce4+ occurred under reducing conditions. The size of the Pt clusters was also determined from the data. The Pt was found to always exist in the metallic state. The Zr4+ was not seen to change during all treatments. For the powder samples the Ce4+ was readily reduced to approximately 60%. Pt was found to be initially oxidised with the % of metallic Pt increasing with reduction temperature. Again no change in the Zr was observed.

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The study of interfacial reactions of nickel thin films on GaAs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074616 ◽

1983 ◽

Vol 41 ◽

pp. 156-157

Author(s):

L.J. Chen ◽

Y.F. Hsieh

Keyword(s):

Thin Films ◽

Integrated Circuits ◽

Interfacial Reactions ◽

Metal Contacts ◽

Nickel Thin Films ◽

Thin Foils ◽

The Status ◽

Si Doped ◽

Electron Microscopes

One measure of the maturity of a device technology is the ease and reliability of applying contact metallurgy. Compared to metal contact of silicon, the status of GaAs metallization is still at its primitive stage. With the advent of GaAs MESFET and integrated circuits, very stringent requirements were placed on their metal contacts. During the past few years, extensive researches have been conducted in the area of Au-Ge-Ni in order to lower contact resistances and improve uniformity. In this paper, we report the results of TEM study of interfacial reactions between Ni and GaAs as part of the attempt to understand the role of nickel in Au-Ge-Ni contact of GaAs.N-type, Si-doped, (001) oriented GaAs wafers, 15 mil in thickness, were grown by gradient-freeze method. Nickel thin films, 300Å in thickness, were e-gun deposited on GaAs wafers. The samples were then annealed in dry N2 in a 3-zone diffusion furnace at temperatures 200°C - 600°C for 5-180 minutes. Thin foils for TEM examinations were prepared by chemical polishing from the GaA.s side. TEM investigations were performed with JE0L- 100B and JE0L-200CX electron microscopes.

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Studies on Water in the Hydration Chamber of a Modified Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069715 ◽

1970 ◽

Vol 28 ◽

pp. 544-545

Author(s):

R. C. Moretz ◽

G. G. Hausner ◽

D. F. Parsons

Keyword(s):

Thin Film ◽

Thin Films ◽

Electron Microscope ◽

Steady State ◽

Room Temperature ◽

Small Mass ◽

Equilibrium Pressure ◽

Biological Objects ◽

Mechanical Pump ◽

Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

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