31 research outputs found
Ferromagnetic (Ga,Mn)As nanowires grown by Mn-assisted molecular beam epitaxy
(Ga,Mn)As nanowires were grown by molecular beam epitaxy using Mn as a growth catalyst on GaAs(001) substrates at 485 °C, i.e., at intermediate temperatures higher than ones used for the growth of (Ga,Mn)As thin films, but lower than the ordinary temperatures of Au-assisted growth of GaAs nanowires. (Ga,Mn)As nanowires obtained with typical lengths between 0.8 and 4 μm and diameters 50–90 nm do not have defects, such as dislocations or precipitates, except for the stacking faults lying parallel to the growth direction. The investigation of magnetic and optical properties has been carried out not only for as-grown samples with nanowires but also for peeled off nanowires from the host substrate. The results obtained demonstrate that (Ga,Mn)As nanowires exhibit ferromagnetic ordering around 70 K.Peer reviewe
Nanowire quantum dots tuned to atomic resonances
Quantum dots tuned to atomic resonances represent an emerging field of hybrid
quantum systems where the advantages of quantum dots and natural atoms can be
combined. Embedding quantum dots in nanowires boosts these systems with a set
of powerful possibilities, such as precise positioning of the emitters,
excellent photon extraction efficiency and direct electrical contacting of
quantum dots. Notably, nanowire structures can be grown on silicon substrates,
allowing for a straightforward integration with silicon-based photonic devices.
In this work we show controlled growth of nanowire-quantum-dot structures on
silicon, frequency tuned to atomic transitions. We grow GaAs quantum dots in
AlGaAs nanowires with a nearly pure crystal structure and excellent optical
properties. We precisely control the dimensions of quantum dots and their
position inside nanowires, and demonstrate that the emission wavelength can be
engineered over the range of at least around . By applying an
external magnetic field we are able to fine tune the emission frequency of our
nanowire quantum dots to the transition of Rb. We use the Rb
transitions to precisely measure the actual spectral linewidth of the photons
emitted from a nanowire quantum dot to be , under
non-resonant excitation. Our work brings highly-desirable functionalities to
quantum technologies, enabling, for instance, a realization of a quantum
network, based on an arbitrary number of nanowire single-photon sources, all
operating at the same frequency of an atomic transition.Comment: main text (20 pages, 3 figures) plus supplementary information, Nano
Letters (2018
Anapoles in Free-Standing III–V Nanodisks Enhancing Second-Harmonic Generation
ISSN:1530-6984ISSN:1530-699