Quantum confinement and electroluminescence in ultrathin silicon nanowires fabricated by a maskless etching technique

We present a novel approach for the direct synthesis of ultrathin Si nanowires (NWs) exhibiting room temperature light emission. The synthesis is based on a wet etching process assisted by a metal thin film. The thickness-dependent morphology of the metal layer produces uncovered nanometer-size regions which act as precursor sites for NW formation. The process is cheap, fast, maskless and compatible with Si technology. Very dense arrays of long (several micrometers) and small (diameter of 5–9 nm) NWs have been synthesized. An efficient room temperature luminescence, visible with the naked eye, is observed when NWs are optically excited, exhibiting a blue-shift with decreasing NW size in agreement with quantum confinement effects. A prototype device based on Si NWs has been fabricated showing a strong and stable electroluminescence at low voltages. The relevance and the perspectives of the reported results are discussed, opening the route toward novel applications of Si NWs.

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Role of the Si excess on the excitation of Er doped SiOx

The authors have investigated the role of the Si excess on the photoluminescence properties of Er doped substoichiometric SiOx layers. They demonstrate that the Si excess has two competing roles: when agglomerated to form Si nanoclusters Si-nc’s it enhances the Er excitation efficiency but it also introduces new nonradiative decay channels. When Er is excited through an energy transfer from Si-nc’s, the beneficial effect on the enhanced excitation efficiency prevails and the Er emission increases with increasing Si content. However, when pumped resonantly, the Er luminescence intensity always decreases with increasing Si content. These data are presented and their implications are discussed.

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Sub-250 nm optical gain

Room temperature deep-UV optical gain has been demonstrated in AlGaN/AlN multiple quantum wells structure with strong band-structure potential fluctuations grown by Molecular Beam Epitaxy. A maximum net modal gain of 118 cm-1 has been measured and the transparency threshold of 5 µJ/cm2 was experimentally determined. Amplified Spontaneous Emission results strongly TE-polarized.

This work has been funded by DARPA – Defense Advanced Research Projects Agency CMUVT Program under subcontract from Photon Systems Inc. (2011, March – 2012, March) and performed at Boston University.

Publication output

Conference proceedings

  • Sub-250nm room temperature optical gain from AlGaN materials with strong compositional fluctuations
    E. F. Pecora, W. Zhang, H. Sun, A. Yu. Nikiforov, J. Yin, R. Paiella, T. D. Moustakas, L. Dal Negro
    Bulletin of the American Physical Society, vol. 58, V1.00111
  • Sub-250nm room temperature optical gain from AlGaN/AlN multiple quantum wells structures
    E. F. Pecora, W. Zhang, L. Zhou, D. J. Smith, J. Yin, R. Paiella, L. Dal Negro, T. D. Moustakas
    CLEO: Science and Innovations, CTh3D, CTh3D.5
  • Sub-250nm room-temperature optical gain from AlGaN/AlN multiple quantum dot structures
    E. F. Pecora, W. Zhang, L. Zhou, D. J. Smith, J. Yin, R. Paiella, L. Dal Negro, T. D. Moustakas
    Bulletin of the American Physical Society, vol. 57
  • Room temperature low threshold stimulated emission of electron beam-pumped AlGaN-based deep UV laser structures emitting below 250 nm
    A. Nikiforov, W. Zhang, J. Woodward, J. Yin, E. Pecora, L. Zhou, L. Dal Negro, R. Paiella, D. Smith, T. Moustakas, A. Moldawer
    Bulletin of the American Physical Society, vol. 57

Conference participation

  • APS March Meeting 2013 – Baltimore, MD (USA) March 18 – 22, 2013 Poster presentation, Session V1
  • CLEO Conference 2012 – San Jose, CA (USA) May 6 – 11, 2012 Oral presentation, Session “Low-dimensional Photonic Structures”
  • APS March Meeting 2012 – Boston, MA (USA) February 27 – March 2, 2012 Oral presentation, Session L28

Boston University

PostDoctoral Associate at the Photonics Center of Boston University from 2011, March to 2013, August.

Research projects

Publication output

Conference proceedings

  • Integration of metallic nanostructures on nanowires for modification of their optical properties
    A. Casadei, E. Alarcon-Llado, E. F. Pecora, J. Trevino, C. Forestiere, D. Ruffer, E. Russo-Averchi, F. Matteini, G. Tutuncuoglu, M. Heiss, L. Dal Negro, A. Fontcuberta i Morral
    Frontiers in Nanophotonics, CSF Conference 2015
  • Second harmonic excitation spectroscopy in studies of Fano-type coupling in plasmonic arrays
    G. F. Walsh, J. Tervino, E. F. Pecora, L. Dal Negro
    SPIE Optics + Photonics 2015
  • Engineering light coupling in single nanowire with metal nano-antennas
    A. Casadei, J. Trevino, E. F. Pecora, E. Alarcò- Lladò, D. Ruffer, E. Russo-Averchi, G. Tutuncuoglu, F. Matteini, C. Forestiere, L. Dal Negro, A. Fontcuberta i Morral
    International Conference on One dimensional Nanomaterials ICON 2013
  • Second-harmonic generation from plasmonic nanoantennas and arrays
    A. Capretti, C. Forestiere, E. F. Pecora, G. Walsh, J. Trevino, S. Minissale, L. Dal Negro, G. Miano
    The International Conference on Surface Plasmon Photonics SPP6
  • Sub-250nm room temperature optical gain from AlGaN materials with strong compositional fluctuations
    E. F. Pecora, W. Zhang, H. Sun, A. Yu. Nikiforov, J. Yin, R. Paiella, T. D. Moustakas, L. Dal Negro
    Bulletin of the American Physical Society, vol. 58, V1.00111
  • Second-harmonic generation in substoichiometric silicon nitride layers
    E. F. Pecora, A. Capretti, G. Miano, L. Dal Negro
    Bulletin of the American Physical Society, vol. 58, V1.00119
  • Rare-earth doped Si-rich ZnO for multiband near-infrared light emitting devices
    E. F. Pecora, T. I. Murphy, L. Dal Negro
    Bulletin of the American Physical Society, vol. 58, C23.00004
  • Nanopatterning of optically-active silicon nanowires
    E. F. Pecora, N. Lawrence, P. Gregg, J. Trevino, P. Artoni, A. Irrera, F. Priolo, L. Dal Negro
    Frontiers in Optics (FiO) – Novel Silicon Waveguides and Nanophotonics (FM4E)
  • Sub-250nm room temperature optical gain from AlGaN/AlN multiple quantum wells structures
    E. F. Pecora, W. Zhang, L. Zhou, D. J. Smith, J. Yin, R. Paiella, L. Dal Negro, T. D. Moustakas
    CLEO: Science and Innovations, CTh3D, CTh3D.5
  • Sub-250nm room-temperature optical gain from AlGaN/AlN multiple quantum dot structures
    E. F. Pecora, W. Zhang, L. Zhou, D. J. Smith, J. Yin, R. Paiella, L. Dal Negro, T. D. Moustakas
    Bulletin of the American Physical Society, vol. 57
  • Room temperature low threshold stimulated emission of electron beam-pumped AlGaN-based deep UV laser structures emitting below 250 nm
    A. Nikiforov, W. Zhang, J. Woodward, J. Yin, E. Pecora, L. Zhou, L. Dal Negro, R. Paiella, D. Smith, T. Moustakas, A. Moldawer
    Bulletin of the American Physical Society, vol. 57

Conference participation

  • APS March Meeting 2013 – Baltimore, MD (USA) March 18 – 22, 2013 Poster presentation, Session V1
  • APS March Meeting 2013 – Baltimore, MD (USA) March 18 – 22, 2013 Poster presentation, Session V1
  • APS March Meeting 2013 – Baltimore, MD (USA) March 18 – 22, 2013 Oral presentation, Session C23
  • MRS Fall Meeting 2012 – Boston, MA (USA) November 25 – 30, 2012 Oral presentation, Symposium DD
  • MRS Fall Meeting 2012 – Boston, MA (USA) November 25 – 30, 2012 Oral presentation, Symposium DD
  • MRS Fall Meeting 2012 – Boston, MA (USA) November 25 – 30, 2012 Poster presentation, Symposium Z
  • CLEO Conference 2012 – San Jose, CA (USA) May 6 – 11, 2012 Oral presentation, Session “Low-dimensional Photonic Structures”
  • APS March Meeting 2012 – Boston, MA (USA) February 27 – March 2, 2012 Oral presentation, Session L28

Leadership experience

  • Laboratory Safety Coordinator for the Boston University Research Compliance – Environmental Health & Safety (2011 – 2013)

Teaching activity

  • Substitute lecturer for the EC471 class (Physics of Semiconductor Devices) at Boston University, Spring 2012 semester

University of Catania

Laurea Specialistica (M.Sc. equivalent) in Physics, summa cum laude at University of Catania
Thesis: Ruolo del contenuto di silicio sulla luminescenza di ioni Er in matrici di ossido di silicio substechiometrico (Role of the silicon content in substoichiometric silicon oxide matrices on the Er luminescence)
Advisors: prof. Francesco Priolo, dr. Giorgia Franzò
Date: 2006, October 11

Laurea (B.Sc. equivalent) in Physics, summa cum laude at University of Catania
Thesis: Confinamento quantico in nanocristalli di silicio (Quantum confinement effects in silicon nanocrystals)
Advisors: prof. Francesco Priolo, dr. Domenico Pacifici
Date: 2004, September 30

Publication output

Conference participation