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Anna Fontcuberta i Morral

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Related publications (286)

Local modification of GaAs nanowires induced by laser heating

GaAs nanowires were heated locally under ambient air conditions by a focused laser beam which led to oxidation and formation of crystalline arsenic on the nanowire surface. Atomic force microscopy, photoluminescence and Raman spectroscopy experiments were ...

Institute of Physics2011

Single material band gap engineering in GaAs nanowires

Anna Fontcuberta i Morral

The structural and optical properties of GaAs nanowire with mixed zinc-blende/wurtzite structure are presented. High resolution transmission electron microscopy indicates the presence of a variety of shorter and longer segments of zinc-blende or wurtzite c ...

Amer Inst Physics2011

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

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

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, Emanuele Uccelli, Efthimios Kaxiras, Jun Ren, Sonia Conesa Boj

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

Untangling the Electronic Band Structure of Wurtzite GaAs Nanowires by Resonant Raman Spectroscopy

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

In semiconductor nanowires, the coexistence of wurtzite and zinc-blende phases enables the engineering of the electronic structure within a single material. This presupposes an exact knowledge of the band structure in the wurtzite phase. We demonstrate tha ...

American Chemical Society2011

Supercooling of nanoscale Ga drops with controlled impurity levels

Anna Fontcuberta i Morral, Emanuele Uccelli

We use in situ observations by variable temperature transmission electron microscopy on Ga drops at the tips of GaAs nanowires to investigate the phase behavior of nanoscale Ga. Experiments on pure Ga drops are compared with drops containing well-defined l ...

2011

Impact of surfaces on the optical properties of GaAs nanowires

Anna Fontcuberta i Morral, Martin Heiss

The effect of surfaces on the optical properties of GaAs nanowires is evidenced by comparing nanowires with or without an AlGaAs capping shell as a function of the diameter. We find that the optical properties of unpassivated nanowires are governed by Ferm ...

American Institute of Physics2010

Quantum Interference Control of Femtosecond, mu A Current Bursts in Single GaAs Nanowires

Anna Fontcuberta i Morral

A phase-stable superposition of femtosecond pulses from a compact erbium-doped fiber source and their second harmonic is shown to induce ultrashort similar to mu A current bursts in single unbiased GaAs nanowires. Current injection relies on a quantum inte ...

American Chemical Society2010

Position controlled self-catalyzed growth of GaAs nanowires by molecular beam epitaxy

Anna Fontcuberta i Morral

GaAs nanowires are grown by molecular beam epitaxy using a self-catalyzed, Ga-assisted growth technique. Position control is achieved by nano-patterning a SiO2 layer with arrays of holes with a hole diameter of 85 nm and a hole pitch varying between 200 nm ...

Institute of Physics2010

InAs Quantum Dot Arrays Decorating the Facets of GaAs Nanowires

Anna Fontcuberta i Morral, Emanuele Uccelli

InAs quantum dot arrays are obtained on GaAs nanowire facets by molecular beam epitaxy. The GaAs nanowires are first grown by the gallium-assisted catalyst-free method. Decoration of the nanowire facets with InAs quantum dots is achieved only when the face ...

American Chemical Society2010

All-optical coherent control of electrical currents in single GaAs nanowires

Anna Fontcuberta i Morral

A phase-stable superposition of femtosecond pulses and their second harmonic induces ultrashort microampere current bursts in single unbiased GaAs nanowires. Current injection relies on quantum interference of one-and two-photon absorption pathways. © 2010 ...

Optical Society of America2010

Multiple Nanowire Species Synthesized on a Single Chip by Selectively Addressable Horizontal Nanochannels

Anna Fontcuberta i Morral

The synthesis of horizontal porous anodic alumina (PAA) structures with individually addressable channel systems is demonstrated. This was achieved by developing a multicontact design of aluminum finger structures (two to Five contacts) on silicon wafers. ...

American Chemical Society2010

Compensation mechanism in silicon-doped gallium arsenide nanowires

Anna Fontcuberta i Morral, Bernt Ketterer, Emanuele Uccelli

P-type gallium arsenide nanowires were grown with different silicon doping concentrations. The incorporation is monitored by Raman spectroscopy of the local vibrational modes. For Si-concentrations up to 1.4 x 10(18) cm(-3), silicon incorporates mainly in ...

American Institute of Physics2010

Optical Properties of InAs Quantum Dot Array Ensembles with Predetermined Lateral Sizes from 20 to 40 nm

Anna Fontcuberta i Morral, Laura Waller, Emanuele Uccelli

Cleaved edge overgrowth and selective area epitaxy were combined for the synthesis of InAs quantum dot (QD) arrays with lateral sizes from 20 to 40 nm. The optical properties were locally assessed by confocal photoluminescence spectroscopy experiments at l ...

2010

Defect Formation in Ga-Catalyzed Silicon Nanowires

Anna Fontcuberta i Morral, Li Wei, Sonia Conesa Boj, Père Roca i Cabarrocas

The synthesis of silicon nanowires by Ga-assisted plasma enhanced chemical vapor deposition (PECVD) has been recently demonstrated. In the present work, we study in detail the structural characteristics of the synthesized nanowires. High resolution transmi ...

American Chemical Society2010

Thermal conductivity of GaAs nanowires studied by micro-Raman spectroscopy combined with laser heating

Anna Fontcuberta i Morral, Emanuele Uccelli

The thermal properties of freely suspended GaAs nanowires are investigated by applying a method which relies on laser heating and the determination of the local temperature by Raman spectroscopy. In order to determine the values for the thermal conductivit ...

American Institute of Physics2010

Growth study of indium-catalyzed silicon nanowires by plasma enhanced chemical vapor deposition

Anna Fontcuberta i Morral, Libo Yu, Sonia Conesa Boj, Père Roca i Cabarrocas

Indium was used as a catalyst for the synthesis of silicon nanowires in a plasma enhanced chemical vapor deposition reactor. In order to foster the catalytic activity of indium, the indium droplets had to be exposed to a hydrogen plasma prior to nanowire g ...

2010

Spatially resolved Raman spectroscopy on indium-catalyzed core-shell germanium nanowires: size effects

Anna Fontcuberta i Morral, Tonko Garma, Martin Heiss

The structure of indium-catalyzed germanium nanowires is investigated by atomic force microscopy, scanning confocal Raman spectroscopy and transmission electron microscopy. The nanowires are formed by a crystalline core and an amorphous shell. We find that ...

Institute of Physics2010

P-Doping Mechanisms in Catalyst-Free Gallium Arsenide Nanowires

Anna Fontcuberta i Morral, Carlo Colombo, Tonko Garma, Bernt Ketterer, Emanuele Uccelli, Marco Nicotra

Doped catalyst-free GaAs nanowires have been grown by molecular beam epitaxy with the gallium-assisted method. The spatial dependence of the dopant concentration and resistivity have been measured by Raman spectroscopy and four point electrical measurement ...

American Chemical Society2010

Structural and optical properties of high quality zinc-blende/wurtzite GaAs nanowire heterostructures

Anna Fontcuberta i Morral, Sonia Conesa Boj

The structural and optical properties of three different kinds of GaAs nanowires with 100% zinc-blende structure and with an average of 30% and 70% wurtzite are presented. A variety of shorter and longer segments of zinc-blende or wurtzite crystal phases a ...

2009

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