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.
What is the difference between the skin of the Statue of Liberty in New York, and an electric wire? Both are made of the same material (copper), but they have different properties because of the shape. Now, get your shrinking machine and make your electric wire smaller than one of your hair. Do you expect the wire to keep the same properties? Nope, of course!
You can do really amazing thing just changing the shape and the size of any material. This is what I did to enable new light sources made of silicon. All our electronics devices are made of silicon. Unfortunately, it cannot emit light by itself. But, if you fabricate a silicon wire smaller than a virus, things will change.
I investigated the growth of silicon and germanium nanowires by a self-assembled method, using electron beam evaporation. This is a relatively unexploited technique that offers a pathway towards high throughput production. By properly varying the experimental parameters of the evaporation it is possible to define the length, density and crystallographic orientation of the wires. The structural properties have been correlated to the atomistic growth mechanism. Moreover, we explored the possibility to bend and restore the wires. Ion beam irradiation amorphizes the nanowires, causing their bending in the direction opposite to the beam. A full recovery is possible after thermal annealing.
I explored a top-down approach as well. Metal-Assisted Chemical Etching is a full VLSI compatible process to grow very thin nanowires of arbitrary length and controlled doping. Room-temperature photoluminescence and electroluminescence has been demonstrated from silicon nanowires. Moreover, I introduced an innovative approach, based on the combination of standard Electron Beam Lithography and reactive ion etching, for nanopatterning nanowires in any arbitrary geometry. We demonstrate broadband photoluminescence enhancement up to approximately one order of magnitude after a reliable engineering of periodic and aperiodic array patterns.
These projects have been funded partly by University of Catania and CSFNSM (Growth and characterization of Si and Ge nanowires), and performed during my PhD course.
Silicon Nanowires Light Emitting Devices at Room Temperature in Nano-Optics for Enhancing Light-Matter Interactions on a Molecular Scale – Di Bartolo, Baldassare; Collins, John (Eds.) P. Artoni, A. Irrera, G. Franzo, B. Fazio, M. Galli, E. F. Pecora, F. Iacona, F. Priolo Springer (2013), ISBN: 978-9400753129
Conference participation
E-MRS Fall Meeting 2010 – Warsaw (PL) September 13-17, 2010 Oral presentation, Symposium E
International School on “Materials for Renewable Energies” – Erice (TP, Italy) May 28 – June 2, 2010 Poster session
E-MRS 2009 – Strasbourg (F) June 8-12, 2009 Oral presentation, Symposium I
NODE International Summer School – Cortona (AR, Italy) July 1-5, 2008 Poster session
XV International Winter School on “New Developments in Solid State Physics” – Bad HofGastein (Salzburg, AT) February 18-22, 2008
XIII National School of Materials Science – Bressanone (Bz, Italy) September 30 – October 9, 2007 Poster session
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.
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
I joined Stanford University in September 2013 and I was a PostDoctoral Scholar in the group of Prof. Mark Brongersma till May 2016. This is one of the best environments I have been working in during my professional life. Located in the heart of California’s Silicon Valley, it is really one of the world’s leading teaching and research universities. I tried to take advantages of as many as possible opportunities offered by the Farm.
Broadband, polarization-independent, omnidirectional, metamaterial-based antireflection coating for solar cells M. L. Brongersma, C. E. A. Cordaro, E. F. Pecora Provisional patent
Leadership experience
Selected as group facilitator for the Management Matters class organized and offered by the Office of the Vice Provost for Graduate Education at Stanford University
Admitted at the full time Stanford Ignite program by the Stanford Graduate School of Business (Summer 2015)
Admitted at the Stanford IFarm program by the Office of Technology Licensing (Winter 2014)
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
Growth and characterization of Si and Ge nanowires, funded by Centro Siciliano di Fisica Nucleare e Struttura della Materia (2009, November – 2010, December)
Silicon Nanowires Light Emitting Devices at Room Temperature in Nano-Optics for Enhancing Light-Matter Interactions on a Molecular Scale – Di Bartolo, Baldassare; Collins, John (Eds.) P. Artoni, A. Irrera, G. Franzo, B. Fazio, M. Galli, E. F. Pecora, F. Iacona, F. Priolo Springer (2013), ISBN: 978-9400753129
