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183 results on '"Giangregorio, Maria M"'

1. Interlaboratory study on Sb2S3 interplay between structure, dielectric function, and amorphous-to-crystalline phase change for photonics

Author

Gutiérrez, Yael, Ovvyan, Anna P., Santos, Gonzalo, Juan, Dilson, Rosales, Saul A., Junquera, Javier, García-Fernández, Pablo, Dicorato, Stefano, Giangregorio, Maria M., Dilonardo, Elena, Palumbo, Fabio, Modreanu, Mircea, Resl, Josef, Ishchenko, Olga, Garry, Guy, Jonuzi, Tigers, Georghe, Marin, Cobianu, Cornel, Hingerl, Kurt, Cobet, Christoph, Moreno, Fernando, Pernice, Wolfram H.P., and Losurdo, Maria

Published
2024
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3. Layered Gallium Monosulfide as Phase‐Change Material for Reconfigurable Nanophotonic Components On‐Chip

Author

Gutiérrez, Yael, primary, Dicorato, Stefano, additional, Ovvyan, Anna P., additional, Brückerhoff‐Plückelmann, Frank, additional, Resl, Josef, additional, Giangregorio, Maria M, additional, Hingerl, Kurt, additional, Cobet, Christoph, additional, Schiek, Manuela, additional, Duwe, Matthias, additional, Thiesen, Peter H., additional, Pernice, Wolfram H. P., additional, and Losurdo, Maria, additional

Published
2023
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4. Layered Gallium Monosulfide as Phase‐Change Material for Reconfigurable Nanophotonic Components On‐Chip.

Author

Gutiérrez, Yael, Dicorato, Stefano, Ovvyan, Anna P., Brückerhoff‐Plückelmann, Frank, Resl, Josef, Giangregorio, Maria M, Hingerl, Kurt, Cobet, Christoph, Schiek, Manuela, Duwe, Matthias, Thiesen, Peter H., Pernice, Wolfram H. P., and Losurdo, Maria

Subjects
OPTICAL dispersion, GALLIUM, OPTICAL modulators, PHASE change materials, PHASE transitions, PHASE modulation, DATA transmission systems
Abstract

The demand for information processing at ultrahigh speed with large data transmission capacity is continuously rising. Necessary building blocks for on‐chip photonic integrated circuits (PICs) are reconfigurable integrated low‐loss high‐speed modulators and switches. Phase change materials (PCMs) provide unique opportunities for integration into PICs. Here, the investigation of layered gallium monosulfide (GaS) as a novel low‐loss PCM from infrared to optical frequencies is pioneered, with high index contrast (Δn ≈0.5) at the optical telecommunication band. The GaS bandgap switches from 1.5 ± 0.2 eV for the amorphous state to 2.1 ± 0.1 eV for the crystalline state. It is demonstrated that the reversible GaS amorphous‐to‐crystalline phase transition can be operated thermally and by picosecond green (532 nm) laser irradiation. The design of a reconfigurable integrated optical modulator on‐chip based on Mach‐Zehnder Interferometers (MZI) with the GaS PCM cell deposited on one of the arms for application is presented at the telecommunication wavelength of λ = 1310 nm, where the standard single mode optical fiber exhibits zero chromatic dispersion, and at λ = 1550 nm, where a minimum optical loss of 0.22 dB km−1 is obtained. This opens the route to applications such as reconfigurable modulators, beam steering using phase modulation, and photonic neural networks. [ABSTRACT FROM AUTHOR]

Published
2024
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8. Stability of Nanometer-Thick Layered Gallium Chalcogenides and Improvements via Hydrogen Passivation.

Author

Gutiérrez, Yael, Dicorato, Stefano, Dilonardo, Elena, Palumbo, Fabio, Giangregorio, Maria M., and Losurdo, Maria

Abstract

The gallium monochalcogenides family, comprising gallium sulfide (GaS), gallium selenide (GaSe), and gallium telluride (GaTe), is capturing attention for its applications in energy storage and production, catalysis, photonics, and optoelectronics. This interest originates from their properties, which include an optical bandgap larger than those of most common transition metal dichalcogenides, efficient light absorption, and significant carrier mobility. For any application, stability to air exposure is a fundamental requirement. Here, we perform a comparative study of the stability of layered GaS, GaSe, and GaTe nanometer-thick films down to a few layers with the goal of identifying the most suitable Ga chalcogenide for future integration in photonic and optoelectronic devices. Our study unveils a trend of decreasing air stability from sulfide to selenide and finally to telluride. Furthermore, we demonstrate a hydrogen passivation process to prevent the oxidation of GaSe with a higher feasibility and durability than other state-of-the-art passivation methods proposed in the literature. [ABSTRACT FROM AUTHOR]

Published
2023
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9. Layered gallium sulfide optical properties from monolayer to CVD crystalline thin films

Author

Gutiérrez, Yael, primary, Juan, Dilson, additional, Dicorato, Stefano, additional, Santos, Gonzalo, additional, Duwe, Matthias, additional, Thiesen, Peter H., additional, Giangregorio, Maria M., additional, Palumbo, Fabio, additional, Hingerl, Kurt, additional, Cobet, Christoph, additional, García-Fernández, Pablo, additional, Junquera, Javier, additional, Moreno, Fernando, additional, and Losurdo, Maria, additional

Published
2022
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11. Interlaboratory study on Sb2S3 interplay between structure, dielectric function, and amorphous-to-crystalline phase change for photonics

Author

Gutiérrez, Yael, primary, Ovvyan, Anna P., additional, Santos, Gonzalo, additional, Juan, Dilson, additional, Rosales, Saul A., additional, Junquera, Javier, additional, García-Fernández, Pablo, additional, Dicorato, Stefano, additional, Giangregorio, Maria M., additional, Dilonardo, Elena, additional, Palumbo, Fabio, additional, Modreanu, Mircea, additional, Resl, Josef, additional, Ishchenko, Olga, additional, Garry, Guy, additional, Jonuzi, Tigers, additional, Georghe, Marin, additional, Cobianu, Cornel, additional, Hingerl, Kurt, additional, Cobet, Christoph, additional, Moreno, Fernando, additional, Pernice, Wolfram H.P., additional, and Losurdo, Maria, additional

Published
2022
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13. Quick and reliable colorimetric reflectometry forthe thickness determination of low-dimensionalQuick and reliable colorimetric reflectometry for the thickness determination of low-dimensional GaS and GaSe exfoliated layers by optical microscopy

Author

Gutiérrez Vela, Yael, Santos Perodia, Gonzalo, Giangregorio Maria M., Dicorato, Stefano, Palumbo, Fabio, Saiz Vega, José María, Moreno Gracia, Fernando, Losurdo, María, and Universidad de Cantabria

Abstract

Interest in gallium chalcogenides, i.e., gallium sulfide (GaS) and gallium selenide (GaSe), is growing rapidly due to its layered structure compatible with the fabrication of very thin layers by mechanical exfoliation and its wide band gap desirable for the design and fabrication of visible-UV optoelectronic devices. It is well known that the properties of these materials depend on their thickness; therefore, a facile and fast method is needed to infer the thickness of layered GaS and GaSe. Here, we report and validate a colorimetric method based on optical imaging for the quick and reliable quantitative determination of the thickness of exfoliated GaS and GaSe layers although it can be extended to other layered systems. For the validation of the method, the colorimetric computational estimate of the thickness is compared to the value obtained by atomic force microscopy. Further simulation of GaS and GaSe layers on different substrates of interest for different technological applications is provided as a quick guide for the rapid and reliable thickness determination of GaS and GaSe layers on various substrates. Funding. European Union’s Horizon 2020 research and innovation program (No 899598 – PHEMTRONICS).

Published
2021

14. Analysis of Synthesized Phase Change Materials

Author

Losurdo, Maria, Gutierrez, Yael, Giangregorio, Maria M., Dicorato, Stefano, Bianco, Giuseppe V, Perrota, Alberto, Palumbo, Fabio, Mondreanu, Mircea, Cobet, Christoph, Hingerl, Kurt, Graml, Mario, Resl, Josef, Moreno, Fernando, Santos, Gonzalo, Georghe, Marin, and Cobianu

Abstract

Deliverable D2.1: Analysis of Synthesized Phase Change Materials

Published
2021
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35. Dielectric function and electric properties of germanium thin films prepared by gold mediated crystallization.

Author

Giangregorio, Maria M., Losurdo, Maria, Ambrico, Marianna, Capezzuto, Pio, Bruno, Giovanni, and Tapfer, Leander

Subjects
*AMORPHOUS substances, *GERMANIUM compounds, *CRYSTALLIZATION, *PLASMA-enhanced chemical vapor deposition, *CHEMICAL vapor deposition, *ANNEALING of crystals
Abstract

Crystallization of hydrogenated amorphous germanium (a-Ge:H) thin films deposited by plasma enhanced chemical vapor deposition using the GeH4 and H2 precursors has been investigated. A comparative analysis of the kinetics of the thermal crystallization by annealing to 650 °C and of the gold-mediated crystallization (Au-MMC) is carried out. The impact of the Au-MMC on the microcrystalline Ge film microstructure and electrical properties is discussed. The Au thin layer results in a more dense and ordered structure with lower roughness of the microcrystalline Ge films. In order to describe the Ge crystallization kinetics, the dielectric functions of a-Ge:H and microcrystalline germanium μc-Ge have also been determined by spectroscopic ellipsometry in the range of 0.75-6.0 eV and parametrized using the Tauc-Lorentz dispersion equation. [ABSTRACT FROM AUTHOR]

Published
2006
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36. Interplay between GaN polarity and surface reactivity towards atomic hydrogen.

Author

Losurdo, Maria, Giangregorio, Maria M., Capezzuto, Pio, Bruno, Giovanni, Namkoong, Gon, Doolittle, W. Alan, and Brown, April S.

Subjects
*TEMPERATURE, *DENSITY, *NITRIDES, *HYDROGEN, *ATOMS, *MICROSCOPY, *PHYSICS
Abstract

GaN epitaxial layers have been grown by molecular beam epitaxy (MBE). Low (200 °C) and high (700 °C) temperature nitrided sapphire substrates, and GaN and AlN buffer layers have been used as the platforms for investigating polarity selection processes of GaN grown by RF-MBE, aimed at presenting a comprehensive understanding of the issues of GaN polarity and growth conditions. The results show that Ga-polar GaN results from the use of AlN buffer layers, and when the substrate/bulk interface has a Ga- or Al-rich interface. In contrast, a large density of N-polar domains is found when GaN epitaxial films are grown on GaN buffer layers on sapphire when nitrided at 200 °C. The impact of the polarity of GaN on the interaction of GaN surfaces with atomic hydrogen is also studied. A different reaction rate and reaction extent is found for N- and Ga-polar GaN with atomic hydrogen, with N-polar GaN exhibiting greater reactivity. It is also demonstrated that the reactivity of GaN with atomic hydrogen coupled with surface potential measurements exploiting Kelvin probe microscopy is an alternative approach to determining the polarity of GaN films, and identifying the presence of inversion domains. Finally, the impact of GaN polarity on electrical properties of AlGaN/GaN heterojunction structures is also shown. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2004
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39. Sustainable and Tunable Mg/MgO Plasmon-Catalytic Platform for the Grand Challenge of SF6Environmental Remediation

Author

Gutiérrez, Yael, Giangregorio, Maria M., Palumbo, Fabio, González, Francisco, Brown, April S., Moreno, Fernando, and Losurdo, Maria

Abstract

Sulfur hexafluoride (SF6) is one of the most harmful greenhouse gases producing environmental risks. Therefore, developing ways of degrading SF6without forming hazardous products is increasingly important. Herein, we demonstrate for the first time the plasmon-catalytic heterogeneous degradation of SF6into nonhazardous MgF2and MgSO4products by nontoxic and sustainable plasmonic magnesium/magnesium oxide (Mg/MgO) nanoparticles, which are also effective as a plasmon-enhanced SF6chemometric sensor. The main product depends on the excitation wavelength; when the localized surface plasmon resonance (LSPR) is in the ultraviolet, then MgF2forms, while visible light LSPR results in MgSO4. Furthermore, Mg/MgO platforms can be regenerated in few seconds by hydrogen plasma treatment and can be reused in a new cycle of air purification. Therefore, this research first demonstrates effectiveness of Mg/MgO plasmon-catalysis enabling environmental remediation with the concurrent functionalities of monitoring, degrading, and detecting sulfur and fluorine gases in the atmosphere.

Published
2020
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48. Enhancing Chemical and Optical Stability of Silver Nanostructures by Low-Temperature Hydrogen Atoms Processing

Author

Losurdo, Maria, primary, Bergmair, Iris, additional, Giangregorio, Maria M., additional, Dastmalchi, Babak, additional, Bianco, Giuseppe V., additional, Helgert, Christian, additional, Pshenay-Severin, Ekaterina, additional, Falkner, Matthias, additional, Pertsch, Thomas, additional, Kley, Ernst-Bernhard, additional, Huebner, Uwe, additional, Verschuuren, Marc A., additional, Muehlberger, Michael, additional, Hingerl, Kurt, additional, and Bruno, Giovanni, additional

Published
2012
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50. Interplay between solid-state organization and optical properties of thin films of poly-arylene-vinylene and -difluorinated vinylene: Fullerene blends

Author

Dilonardo, Elena, primary, Cardone, Antonio, additional, Martinelli, Carmela, additional, Giangregorio, Maria M., additional, Losurdo, Maria, additional, Capezzuto, Pio, additional, Farinola, Gianluca M., additional, Babudri, Francesco, additional, Naso, Francesco, additional, and Bruno, Giovanni, additional

Published
2012
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