Browsing by Author "Othonos, Andreas S."
Now showing items 1-20 of 156
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Absolute nonradiative energy-conversion-efficiency spectra in Ti3+:Al2O3 crystals measured by noncontact quadrature photopyroelectric spectroscopy
Mandelis, Andreas; Vanniasinkam, J.; Budhudu, S.; Othonos, Andreas S.; Kokta, M. (1993)Photopyroelectric spectroscopy (PPES) was used in a noncontact experimental configuration to obtain high-resolution absolute spectra of the optical-to-thermal energy-conversion efficiency (nonradiative coefficient), ηNR(λ), ...
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Broad compositional tunability of indium tin oxide nanowires grown by the vapor-liquid-solid mechanism
Zervos, Matthew; Mihailescu, C. N.; Giapintzakis, Ioannis; Luculescu, C. R.; Florini, N.; Komninou, Ph; Kioseoglou, J.; Othonos, Andreas S. (2014)Indium tin oxide nanowires were grown by the reaction of In and Sn with O2 at800 °C via the vapor-liquid-solid mechanism on 1 nm Au/Si(001). We obtain Sn doped In2O3 nanowires having a cubic bixbyite crystal structure by ...
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Article
Carrier dynamics and conductivity of SnO 2 nanowires investigated by time-resolved terahertz spectroscopy
Tsokkou, Demetra; Othonos, Andreas S.; Zervos, Matthew (2012)THz spectroscopy has been applied to investigate the photo-induced and intrinsic conductivity in SnO 2 nanowires using the Drude-Smith model. The refractive index of the nanowires was found to decrease from 2.4 to 2.1 with ...
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Article
Carrier dynamics in beta-Ga2O3 nanowires
Othonos, Andreas S.; Zervos, Matthew; Christofides, Constantinos (2010)Carrier dynamics have been investigated in beta-Ga2O3 nanowires (NWs) grown by the vapor-liquid-solid mechanism, using ultrashort transient absorption spectroscopy in conjunction with time-correlating single photon counting ...
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Article
Carrier dynamics in InS nanowires grown via chemical vapor deposition
Othonos, Andreas S.; Zervos, Matthew (2010)Transient femtosecond absorption spectroscopy and timecorrelating single photon counting (TCSPC) photoluminescence (PL) were employed to study InS nanowires (NWs) grown by chemical vapor deposition (CVD) and determine the ...
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Carrier relaxation dynamics in SnxNy nanowires grown by chemical vapor deposition
Othonos, Andreas S.; Zervos, Matthew (2009)Carrier relaxation dynamics in tin nitride (SnxNy) nanowires have been investigated using femtosecond transient absorption spectroscopy. The nanowires were grown directly on quartz using chemical vapor deposition and had ...
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Article
Chapter 3 Photoluminescence and Raman Scattering of Ion Implanted Semiconductors. Influence of Annealing
Othonos, Andreas S.; Christofides, Constantinos (1997)
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Conference Object
Characteristics of fiber grating sensors and their relation to manufacturing techniques
Alavie, A. Tino; Maaskant, Robert; Stubbe, Raoul; Othonos, Andreas S.; Ohn, Myo M.; Sahlgren, Bengt; Measures, Raymond M. (Society of Photo-Optical Instrumentation Engineers, 1995)This work examines the effects of different manufacturing techniques of fiber optic intracore Bragg gratings on their sensing and system parameters. Specifically, we have looked at tolerance with respect to center wavelength, ...
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Article
Characterization of reflectivity inversion, alpha- and beta-phase transitions and nanostructure formation in hydrogen activated thin Pd films on silicon based substrates
Kalli, Kyriacos; Othonos, Andreas S.; Christofides, Constantinos (2002)Optically thin palladium metal films evaporated on different silicon based substrates are investigated following exposure to different concentrations of hydrogen gas in air. Laser modulated reflectance off the palladium ...
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Article
Concentration and excitation effects on the exciton dynamics of poly(3-hexylthiophene)/PbS quantum dot blend films
Tsokkou, Demetra; Itskos, Grigorios; Choulis, Stelios A.; Yarema, M.; Heiss, W.; Othonos, Andreas S. (2013)The dynamics of photoexcitations in hybrid blends of poly(3-hexylthiophene) (P3HT) conjugated polymer donor and oleic-acid capped lead sulfide (PbS) quantum dot (QD) acceptors of different concentrations - for light ...
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Article
CONDENSED MATTER
Kalli, Kyriacos; Othonos, Andreas S.; Christofides, Constantinos; Anita Lloyd Spetz; Ingemar Lundstrom (1998)
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Article
Core-shell PbS/Sn:In2O3 and branched PbIn2S4/Sn:In2O3 nanowires in quantum dot sensitized solar cells
Zervos, Matthew; Vasile, Eugeniu; Tanasǎ, Eugenia; Othonos, Andreas S. (2017)Core-shell PbS/Sn:In2O3 and branched PbIn2S4/Sn:In2O3 nanowires have been obtained via the deposition of Pb over Sn:In2O3 nanowires and post growth processing under H2S between 100 C-200 C and 300 C-500 C respectively. The ...
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Conference Object
Correlation of hot carrier and hot phonon effects in semiconductors on a picosecond time scale
van Driel, Henry M.; Othonos, Andreas S.; Young, Jeff F.; Kelly, Paul J. (Publ by Int Soc for Optical Engineering, 1990)Through simultaneous analysis of picosecond, time-resolved reflectivity and Raman scattering data we have been able to self-consistently relate hot carrier and hot phonon kinetics in bulk, crystalline Germanium. We show ...
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Correlation of hot-phonon and hot-carrier kinetics in Ge on a picosecond time scale
Othonos, Andreas S.; Van Driel, H. M.; Young, J. F.; Kelly, P. J. (1991)We report room-temperature measurements of time-resolved reflectivity from intrinsic crystalline Ge induced and probed by =0.575 m, 2-ps pulses and for photogenerated carrier densities up to 1019 cm-3. These data are used ...
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Article
Current Transport Properties of CuS/Sn:In2O3 versus CuS/SnO2 Nanowires and Negative Differential Resistance in Quantum Dot Sensitized Solar Cells
Zervos, Matthew; Vasile, Eugeniu; Tanasǎ, Eugenia; Karageorgou, E.; Othonos, Andreas S. (2016)The structural, optical, and electrical transport properties of nanowires obtained by the deposition of Cu over Sn doped In2O3 and SnO2 nanowires followed by processing under H2S between 100 and 500°C have been investigated ...
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Defect states of chemical vapor deposition grown GaN nanowires: Effects and mechanisms in the relaxation of carriers
Tsokkou, Demetra; Othonos, Andreas S.; Zervos, Matthew (2009)Carrier relaxation in GaN nanowires, grown by atmospheric pressure chemical vapor deposition, via direct nitridation of Ga with NH3 at 950 °C has been investigated in detail. Differential absorption measurements reveal a ...
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Article
Determination of critical points on silicon nanofilms: Surface and quantum confinement effects
Lioudakis, Emmanouil E.; Othonos, Andreas S.; Nassiopoulou, Androula Galiouna (2008)In this work, we present a comprehensive study of the optical properties of nanocrystalline silicon films with thickness varied from 5 to 30 nm. Spectroscopic ellipsometry is employed to determine the dielectric functions ...
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Determination of Erbium Distribution in Optical Fibers Using Confocal Optical Microscopy
Uttamchandani, D.; Othonos, Andreas S.; Hubert, M. (1994)Confocal fluorescence microscopy has been used to detect the 565 nm wavelength fluorescence generated from Er+3 ions present in erbium doped optical fibers, thereby enabling the concentration profile of these ions in the ...
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Diagnostics of nonradiative defects in the bulk and surface of brewster-cut Ti:sapphire laser materials using photothermal radiometry
Vanniasinkam, J.; Munidasa, M.; Othonos, Andreas S.; Kokta, M.; Mandelis, Andreas (1997)The understanding of the problem of nonradiative energy conversion in solid-state laser materials is a key factor in improving the overall efficiency of solid-state lasers. Furthermore, the reduction of the heat generated ...
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Article
Direct observation of excitons in polymer/carbon nanotube composites at room temperature: The influence of nanotube concentration
Lioudakis, Emmanouil E.; Kanari, C.; Othonos, Andreas S.; Alexandrou, Ioannis (2008)In this work, we have employed spectroscopic ellipsometry technique to study the optical properties of polymer/carbon nanotube (CN) composites as a function of nanotube concentration. Using a two-layer structural model ...