Browsing by Author "Nassiopoulou, Androula Galiouna"
Now showing items 1-14 of 14
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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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Ellipsometric analysis of ion-implanted polycrystalline silicon films before and after annealing
Lioudakis, Emmanouil E.; Nassiopoulou, Androula Galiouna; Othonos, Andreas S. (2006)A study of arsenic ion-implanted polycrystalline silicon films before and after annealing at various temperatures has been performed using spectroscopic ellipsometry in the ultraviolet to the visible spectral region. Using ...
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Femtosecond carrier dynamics in implanted and highly annealed polycrystalline silicon
Lioudakis, Emmanouil E.; Nassiopoulou, Androula Galiouna; Othonos, Andreas S. (2006)We have studied the ultrafast optical response of highly implanted and highly annealed polycrystalline silicon films using 400 nm ultrashort amplified pulses with fluence ranging between 8 mJ cm-2 to 56 mJ cm -2. Transient ...
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Influence of grain size on ultrafast carrier dynamics in thin nanocrystalline silicon films
Lioudakis, Emmanouil E.; Othonos, Andreas S.; Nassiopoulou, Androula Galiouna; Lioutas, Ch B.; Frangis, N. (2007)The ultrafast carrier dynamics in thin nanocrystalline silicon films (10 and 20 nm thick) on quartz over a broad spectral range using optical pumping at a moderate fluence of 2.5 mJ cm2 were studied. The films were composed ...
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Pb doping of In2O3 and their conversion to highly conductive PbS/In2S3-3xO3x nanowires with infra red emission
Zervos, Matthew; Othonos, Andreas S.; Gianetta, V.; Nassiopoulou, Androula Galiouna (2016)We have grown Pb doped In2O3 nanowires at 800°C which have the cubic bixbyite crystal structure of In2O3 and contain orthorhombic α-PbO. These had resistances up to ≈10 Ω and exhibited photoluminescence at 2.5 eV but we ...
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Probing carrier dynamics in implanted and annealed polycrystalline silicon thin films using white light
Lioudakis, Emmanouil E.; Othonos, Andreas S.; Nassiopoulou, Androula Galiouna (2006)Polycrystalline silicon thin film samples implanted and annealed at various temperatures have been studied using ultrafast laser pulse excitation. Nondegenerate pump-probe technique has been utilized to investigate carrier ...
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Quantum confinement and interface structure of Si nanocrystals of sizes 3-5 nm embedded in a-SiO2
Lioudakis, Emmanouil E.; Othonos, Andreas S.; Hadjisavvas, G. C.; Kelires, P. C.; Nassiopoulou, Androula Galiouna (2007)Spectroscopic ellipsometry and Monte Carlo simulations are employed to answer the fundamental question whether the energy gaps of Si nanocrystals with sizes in the range of 3-5 nm, which are embedded in amorphous silica, ...
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The role of surface vibrations and quantum confinement effect to the optical properties of very thin nanocrystalline silicon films
Lioudakis, Emmanouil E.; Antoniou, Antreas; Othonos, Andreas S.; Christofides, Constantinos; Nassiopoulou, Androula Galiouna; Lioutas, Ch B.; Frangis, N. (2007)We report on a spectroscopic study of very thin nanocrystalline silicon films varying between 5 and 30 nm. The role of quantum confinement effect and surface passivation of nanograins in optical properties are examined in ...
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Sn doped β-Ga2O3 and β-Ga2S3 nanowires with red emission for solar energy spectral shifting
Zervos, Matthew; Othonos, Andreas S.; Gianneta, V.; Travlos, A.; Nassiopoulou, Androula Galiouna (2015)Sn doped β-Ga2O3 nanowires have been grown on Si(001) via the vapor-liquid-solid mechanism at 800 °C over a broad range of compositions. These have a monoclinic β-Ga2O3 crystal structure and minimum resistances for 1-2 at. ...
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Structure, morphology, and photoluminescence of porous Si nanowires: Effect of different chemical treatments
Leontis, I.; Othonos, Andreas S.; Nassiopoulou, Androula Galiouna (2013)The structure and light-emitting properties of Si nanowires (SiNWs) fabricated by a single-step metal-assisted chemical etching (MACE) process on highly boron-doped Si were investigated after different chemical treatments. ...
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Surface-related states in oxidized silicon nanocrystals enhance carrier relaxation and inhibit auger recombination
Othonos, Andreas S.; Lioudakis, Emmanouil E.; Nassiopoulou, Androula Galiouna (2008)We have studied ultrafast carrier dynamics in oxidized silicon nanocrystals (NCs) and the role that surface-related states play in the various relaxation mechanisms over a broad range of photon excitation energy corresponding ...
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Ultrafast carrier dynamics in highly implanted and annealed polycrystalline silicon films
Lioudakis, Emmanouil E.; Nassiopoulou, Androula Galiouna; Othonos, Andreas S. (2005)We have studied the ultrafast optical response of highly implanted and annealed polycrystalline silicon films. One-micron thin polycrystalline silicon samples-on-quartz implanted with As ions at a high dose of 2 × 10 16 ...
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Ultrafast time-resolved spectroscopy of Si nanocrystals embedded in SiO2 matrix
Lioudakis, Emmanouil E.; Emporas, A.; Othonos, Andreas S.; Nassiopoulou, Androula Galiouna (2009)In this work, we present a comprehensive study of ultrafast transient photoinduced absorption of silicon nanocrystals (NCs) embedded in SiO2 matrix. The samples under investigation are single monolayers of Si-NCs embedded ...
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Ultrafast transient photoinduced absorption in silicon nanocrystals: Coupling of oxygen-related states to quantized sublevels
Lioudakis, Emmanouil E.; Othonos, Andreas S.; Nassiopoulou, Androula Galiouna (2007)The authors have studied transient photoinduced absorption in single monolayers of oxidized silicon nanocrystals. Transient photoinduced absorption measurements along with optical absorption and photoluminescence (PL) ...