7 research outputs found
Correction to Ultrathin Au-Alloy Nanowires at the Liquid–Liquid Interface
Correction to Ultrathin Au-Alloy Nanowires at the
Liquid–Liquid Interfac
Ultrathin Au-Alloy Nanowires at the Liquid–Liquid Interface
Ultrathin
bimetallic nanowires are of importance and interest for
applications in electronic devices such as sensors and heterogeneous
catalysts. In this work, we have designed a new, highly reproducible
and generalized wet chemical method to synthesize uniform and monodispersed
Au-based alloy (AuCu, AuPd, and AuPt) nanowires with tunable composition
using microwave-assisted reduction at the liquid–liquid interface.
These ultrathin alloy nanowires are below 4 nm in diameter and about
2 μm long. Detailed microstructural characterization shows that
the wires have an face centred cubic (FCC) crystal structure, and
they have low-energy twin-boundary and stacking-fault defects along
the growth direction. The wires exhibit remarkable thermal and mechanical
stability that is critical for important applications. The alloy wires
exhibit excellent electrocatalytic activity for methanol oxidation
in an alkaline medium
Ultrasmooth Ru(0001) Films as Templates for Ceria Nanoarchitectures
Single crystalline magnetron sputter-deposited
Ru(0001) epitaxial thin films on c-plane sapphire were prepared and
used as a template for reactive CeO<sub>2</sub> growth. Low-energy
electron microscopy and diffraction, as well as transmission electron
microscopy and atomic force microscopy, experiments were performed
to investigate the crystallinity and morphology of the prepared films.
Multiple cycles of Ar<sup>+</sup> sputtering and high-temperature
annealing produces films of exceptional surface quality. High-temperature
reactive ceria growth leads to perfectly aligned triangular single-crystalline
CeO<sub>2</sub>(111) islands of extraordinary morphological and structural
homogeneity. At the chosen growth conditions, ceria nucleation takes
place only at V-shaped surface defects on the otherwise atomically
flat Ru terraces, opening up the possibility to influence the nucleation
by introducing artificial surface defects using standard etching techniques.
Due to their high crystallinity and extraordinary surface quality,
these substrates present a low-cost alternative to Ru single crystals
for model studies in heterogeneous catalysis and also allow for the
use of destructive investigation techniques and irreversible surface
modifications
Axial Growth Characteristics of Optically Active InGaAs Nanowire Heterostructures for Integrated Nanophotonic Devices
III–V semiconductor nanowire (NW) heterostructures
with
axial InGaAs active regions hold large potential for diverse on-chip
device applications, including site-selectively integrated quantum
light sources, NW lasers with high material gain, as well as resonant
tunneling diodes and avalanche photodiodes. Despite various promising
efforts toward high-quality single or multiple axial InGaAs heterostacks
using noncatalytic growth mechanisms, the important roles of facet-dependent
shape evolution, crystal defects, and the applicability to more universal
growth schemes have remained elusive. Here, we report the growth of
optically active InGaAs axial NW heterostructures via completely catalyst-free,
selective-area molecular beam epitaxy directly on silicon (Si) using
GaAs(Sb) NW arrays as tunable, high-uniformity growth templates and
highlight fundamental relationships between structural, morphological,
and optical properties of the InGaAs region. Structural, compositional,
and 3D-tomographic characterizations affirm the desired directional
growth along the NW axis with no radial growth observed. Clearly distinct
luminescence from the InGaAs active region is demonstrated, where
tunable array–geometry parameters and In content up to 20%
are further investigated. Based on the underlying twin-induced growth
mode, we further describe the facet-dependent shape and interface
evolution of the InGaAs segment and its direct correlation with emission
energy
Axial Growth Characteristics of Optically Active InGaAs Nanowire Heterostructures for Integrated Nanophotonic Devices
III–V semiconductor nanowire (NW) heterostructures
with
axial InGaAs active regions hold large potential for diverse on-chip
device applications, including site-selectively integrated quantum
light sources, NW lasers with high material gain, as well as resonant
tunneling diodes and avalanche photodiodes. Despite various promising
efforts toward high-quality single or multiple axial InGaAs heterostacks
using noncatalytic growth mechanisms, the important roles of facet-dependent
shape evolution, crystal defects, and the applicability to more universal
growth schemes have remained elusive. Here, we report the growth of
optically active InGaAs axial NW heterostructures via completely catalyst-free,
selective-area molecular beam epitaxy directly on silicon (Si) using
GaAs(Sb) NW arrays as tunable, high-uniformity growth templates and
highlight fundamental relationships between structural, morphological,
and optical properties of the InGaAs region. Structural, compositional,
and 3D-tomographic characterizations affirm the desired directional
growth along the NW axis with no radial growth observed. Clearly distinct
luminescence from the InGaAs active region is demonstrated, where
tunable array–geometry parameters and In content up to 20%
are further investigated. Based on the underlying twin-induced growth
mode, we further describe the facet-dependent shape and interface
evolution of the InGaAs segment and its direct correlation with emission
energy
Axial Growth Characteristics of Optically Active InGaAs Nanowire Heterostructures for Integrated Nanophotonic Devices
III–V semiconductor nanowire (NW) heterostructures
with
axial InGaAs active regions hold large potential for diverse on-chip
device applications, including site-selectively integrated quantum
light sources, NW lasers with high material gain, as well as resonant
tunneling diodes and avalanche photodiodes. Despite various promising
efforts toward high-quality single or multiple axial InGaAs heterostacks
using noncatalytic growth mechanisms, the important roles of facet-dependent
shape evolution, crystal defects, and the applicability to more universal
growth schemes have remained elusive. Here, we report the growth of
optically active InGaAs axial NW heterostructures via completely catalyst-free,
selective-area molecular beam epitaxy directly on silicon (Si) using
GaAs(Sb) NW arrays as tunable, high-uniformity growth templates and
highlight fundamental relationships between structural, morphological,
and optical properties of the InGaAs region. Structural, compositional,
and 3D-tomographic characterizations affirm the desired directional
growth along the NW axis with no radial growth observed. Clearly distinct
luminescence from the InGaAs active region is demonstrated, where
tunable array–geometry parameters and In content up to 20%
are further investigated. Based on the underlying twin-induced growth
mode, we further describe the facet-dependent shape and interface
evolution of the InGaAs segment and its direct correlation with emission
energy
Axial Growth Characteristics of Optically Active InGaAs Nanowire Heterostructures for Integrated Nanophotonic Devices
III–V semiconductor nanowire (NW) heterostructures
with
axial InGaAs active regions hold large potential for diverse on-chip
device applications, including site-selectively integrated quantum
light sources, NW lasers with high material gain, as well as resonant
tunneling diodes and avalanche photodiodes. Despite various promising
efforts toward high-quality single or multiple axial InGaAs heterostacks
using noncatalytic growth mechanisms, the important roles of facet-dependent
shape evolution, crystal defects, and the applicability to more universal
growth schemes have remained elusive. Here, we report the growth of
optically active InGaAs axial NW heterostructures via completely catalyst-free,
selective-area molecular beam epitaxy directly on silicon (Si) using
GaAs(Sb) NW arrays as tunable, high-uniformity growth templates and
highlight fundamental relationships between structural, morphological,
and optical properties of the InGaAs region. Structural, compositional,
and 3D-tomographic characterizations affirm the desired directional
growth along the NW axis with no radial growth observed. Clearly distinct
luminescence from the InGaAs active region is demonstrated, where
tunable array–geometry parameters and In content up to 20%
are further investigated. Based on the underlying twin-induced growth
mode, we further describe the facet-dependent shape and interface
evolution of the InGaAs segment and its direct correlation with emission
energy