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Martin Heiss

Cette personne n’est plus à l’EPFL

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Publications associées (35)

Magnetic states of an individual Ni nanotube probed by anisotropic magnetoresistance

Anna Fontcuberta i Morral, Martin Heiss, Daniel Rüffer, Eleonora Russo, Dirk Grundler

Defined magnetization states in magnetic nanotubes could be the basic building blocks for future memory elements. To date, it has been extremely challenging to measure the magnetic states at the single-nanotube level. We investigate the magnetization state ...

Royal Soc Chemistry2012

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

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

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

Vertical "III-V" V-Shaped Nanomembranes Epitaxially Grown on a Patterned Si[001] Substrate and Their Enhanced Light Scattering

Anna Fontcuberta i Morral, Martin Heiss, Anna Dalmau Mallorquí, Sonia Conesa Boj, Eleonora Russo, Ludovit Pavel Zweifel

We report on a new form of III-IV compound semiconductor nanostructures growing epitaxially as vertical V-shaped nanomembranes on Si(001) and study their light-scattering properties. Precise position control of the InAs nanostructures in regular arrays is ...

American Chemical Society2012

Polarity Assignment in ZnTe, GaAs, ZnO, and GaN-AlN Nanowires from Direct Dumbbell Analysis

Anna Fontcuberta i Morral, Martin Heiss, Bo Peng

Aberration corrected scanning transmission electron microscopy (STEM) with high angle annular dark field (HAADF) imaging and the newly developed annular bright field (ABF) imaging are used to define a new guideline for the polarity determination of semicon ...

American Chemical Society2012

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

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

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

Fundamental limits in the external quantum efficiency of single nanowire solar cells

Anna Fontcuberta i Morral, Martin Heiss

The fundamental limits for the measurement of the efficiency of single nanowire solar cell devices are presented. We evaluate the effect of the substrate, light polarization, and existence of Mie resonances in the absorption of the solar spectrum for nanow ...

American Institute of Physics2011

Determination of the band gap and the split-off band in wurtzite GaAs using Raman and photoluminescence excitation spectroscopy

Anna Fontcuberta i Morral, Martin Heiss, Bernt Ketterer

GaAs nanowires with 100% wurtzite structure are synthesized by the vapor-liquid-solid method in a molecular beam epitaxy system, using gold as a catalyst. We use resonant Raman spectroscopy and photoluminescence to determine the position of the crystal-fie ...

2011

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

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

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

Gallium arsenide p-i-n radial structures for photovoltaic applications

Michael Graetzel, Anna Fontcuberta i Morral, Carlo Colombo, Martin Heiss

Gallium arsenide p-i-n radial junctions were fabricated by molecular beam epitaxy. The current-voltage characteristics of single nanowires were measured in the dark and under various illumination conditions including 1.5 AM. The total efficiency was 4.5%. ...

American Institute of Physics2009

Single crystalline and core-shell indium-catalyzed germanium nanowires-a systematic thermal CVD growth study

Anna Fontcuberta i Morral, Martin Heiss, Sonia Conesa Boj

Germanium nanowires were synthesized using thermal chemical vapor deposition (CVD) and indium as a catalyst. The process parameter space for successful growth was studied. By optimizing the growth temperature and gas pressure, high aspect ratio germanium n ...

Institute of Physics2009

Catalyst-free nanowires with axial InxGa1-xAs/GaAs heterostructures

Anna Fontcuberta i Morral, Martin Heiss, Sonia Conesa Boj

Self-catalyzed growth of axial InxGa1-xAs/GaAs heterostructures has been realized by molecular beam epitaxy. The growth of the wires is achieved from gallium/indium alloy droplets that are nucleated in situ. By variation of the In/Ga beam flux during the g ...

Institute of Physics2009

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