Publications de Emanuele Uccelli

Tuning the response of non-allowed Raman modes in GaAs nanowires

Anna Fontcuberta i Morral, Federico Matteini, Esther Alarcon Llado, Gözde Tütüncüoglu, Emanuele Uccelli, Francesca Amaduzzi, Hubert Hautmann

We report on the use of photonic resonances in Raman spectroscopy on single nanowires for the enhancement of forbidden modes and the study of the interaction of phonons with free-carriers. This is achieved by suspending nanowire over a trench and detecting ...

Iop Publishing Ltd2016

Charge carrier generation, relaxation, and recombination in polytypic GaAs nanowires studied by photoluminescence excitation spectroscopy

Pierre Michel Corfdir, Anna Fontcuberta i Morral, Emanuele Uccelli

We report results of a study of polytypic GaAs nanowires using low-temperature photoluminescence excitation spectroscopy. The nanowire ensemble shows a strong absorption at 1.517 eV, as a result of resonant generation of heavy-hole excitons in the zinc-ble ...

American Institute of Physics2013

Three-Dimensional Magneto-Photoluminescence as a Probe of the Electronic Properties of Crystal-Phase Quantum Disks in GaAs Nanowires

Anna Fontcuberta i Morral, Pierre Michel Corfdir, Sonia Conesa Boj, Emanuele Uccelli

Crystal-phase engineering has emerged as a novel method of bandgap engineering, made feasible by the high surface-to-volume ratio of nanowires. There remains intense debate about the exact characteristics of the band structure of the novel crystal phases, ...

Amer Chemical Soc2013

Exciton localization mechanisms in wurtzite/zinc-blende GaAs nanowires

Anna Fontcuberta i Morral, Martin Heiss, Sonia Conesa Boj, Emanuele Uccelli

We investigate the emission properties of excitons in GaAs nanowires containing quantum disks formed by structural alternation between the zinc-blende and wurtzite phases, by means of temperature-dependent photoluminescence. At 10 K the emission from an en ...

American Physical Society (APS)2013

Pressure Tuning of the Optical Properties of GaAs Nanowires

Anna Fontcuberta i Morral, Emanuele Uccelli

The tuning of the optical and electronic properties of semiconductor nanowires can be achieved by crystal phase engineering. Zinc-blende and diamond semiconductors exhibit pressure-induced structural transitions as well as a strong pressure dependence of t ...

American Chemical Society2012

Suppression of three dimensional twinning for a 100% yield of vertical GaAs nanowires on silicon

Anna Fontcuberta i Morral, Martin Heiss, Emanuele Uccelli, Eleonora Russo, Lionel Michelet

Multiple seed formation by three-dimensional twinning at the initial stages of growth explains the manifold of orientations found when self-catalyzed GaAs nanowires grow on silicon. This mechanism can be tuned as a function of the growth conditions by chan ...

2012

Mobility and carrier density in p-type GaAs nanowires measured by transmission Raman spectroscopy

Anna Fontcuberta i Morral, Emanuele Uccelli, Bernt Ketterer

Mobility and carrier density in p-type GaAs nanowires measured by transmission Raman spectroscopy ...

2012

Three-Dimensional Multiple-Order Twinning of Self-Catalyzed GaAs Nanowires on Si Substrates

Anna Fontcuberta i Morral, François Morier-Genoud, Martin Heiss, Emanuele Uccelli, Eleonora Russo, Gabriel Mugny

In this paper we introduce a new paradigm for nanowire growth that explains the unwanted appearance of parasitic nonvertical nanowires. With a crystal structure polarization analysis of the initial stages of GaAs nanowire growth on Si substrates, we demons ...

American Chemical Society2011

In(Ga)As quantum dot formation on group-III assisted catalyst-free InGaAs nanowires

Anna Fontcuberta i Morral, Martin Heiss, Emanuele Uccelli, Bernt Ketterer

Growth of GaAs and InxGa1-xAs nanowires by the group-III assisted molecular beam epitaxy growth method on (001)GaAs/SiO2 substrates is studied in dependence on growth temperature, with the objective of maximizing the indium incorporation. Nanowire growth w ...

Institute of Physics2011

Direct correlation of crystal structure and optical properties in wurtzite/zinc-blende GaAs nanowire heterostructures

Anna Fontcuberta i Morral, Martin Heiss, Sonia Conesa Boj, Emanuele Uccelli, Efthimios Kaxiras, Jun Ren

A method for the direct correlation at the nanoscale of structural and optical properties of single GaAs nanowires is reported. Nanowires consisting of 100% wurtzite and nanowires presenting zinc-blende/wurtzite polytypism are investigated by photoluminesc ...

2011