Herein, we present experimental data on the record length uniformity within the ensembles of semiconductor nanowires. The length distributions of Ga-catalyzed GaAs nanowires obtained by cost-effective lithography-free technique on silicon substrates systematically feature a pronounced sub-Poissonian character. For example, nanowires with the mean length ⟨L⟩ of 2480 nm show a length distribution variance of only 367 nm, which is more than twice smaller than the Poisson variance h⟨L⟩ of 808 nm for this mean length (with h = 0.326 nm as the height of GaAs monolayer). For 5125 nm mean length, the measured variance is 1200 nm against 1671 nm for Poisson distribution. A supporting model to explain the experimental findings is proposed. We speculate that the fluctuation-induced broadening of the length distribution is suppressed by nucleation antibunching, the effect which is commonly observed in individual vapor-liquid-solid nanowires but has never been seen for their ensembles. Without kinetic fluctuations, the two remaining effects contributing to the length distribution width are the nucleation randomness for nanowires emerging from the substrate and the shadowing effect on long enough nanowires. This explains an interesting time evolution of the variance that saturates after a short incubation stage but then starts increasing again due to shadowing, remaining, however, smaller than the Poisson value for a sufficiently long time.

thus paves the way for the important applications spreading from negative refraction, [1][2][3] chiral sensing [4,5] to production of optical field carrying out optical angular momentum for quantum information applications. [6] It has been shown that plasmonic nanostructures forming 1D [7] elements, 2D metasurfaces, [8][9][10] and 3D metamaterials [11] can exhibit linear chiral response due to their own, intrinsic chirality. Also semiconductor nanostructures can exhibit chiral features. [12][13][14][15][16] From the optical point of view, chiral structures possess the ability to rotate the plane of the polarization of electromagnetic waves (optical activity), and give rise to circular dichroism-i.e., the difference in the absorption of right-and lefthanded circular polarized light.Apart from 3D chiral objects, the possibility to obtain optical chirality, i.e., optical activity, with nonchiral elements was studied in the past, [17] but only recently reconsidered. [18,19] This phenomenon is obtained when the experimental configuration composed by both the nonchiral object and the optical incident field is nonsuperimposable on its mirror image. [20] This is called "extrinsic" chirality; in our previous works we have investigated this type of chirality in tilted golden nanowires by means of both linear (reflection and absorption) and nonlinear (second harmonic generation) measurements. [20][21][22][23] III-V semiconductor nanowires (NWs) have been widely investigated since they exhibit good waveguiding properties thus offering a light manipulation at nanoscale. Coupling of the incident light to the discrete leaky waveguide modes above the bandgap in NWs leads to increased resonant absorption, thus paving the way for important applications such as energy harvesting, spectral selectivity, lasing, spin angular momentum generation, etc. [24][25][26][27] Metallic NWs have also been investigated for plasmonic laser applications [28][29][30] and possibility of surface plasmon polaritons excitation. [31] One step further is the partial covering of such NWs with gold: this can induce, along with the proper experiment setup, the symmetry breaking which leads to chiral response.In this paper, for the first time to our knowledge, we report on a circular dichroism behavior from semiconductor hexagonal Semiconductor nanostructures hybridized with metals have been known to offer new opportunities in nonlinear optics, plasmonics, lasing, biosensors; among them GaAs-based nanowires (NWs) hybridized with gold can offer new functionalities, as chiral sensing and light manipulation, as well as circular polarization sources. This study investigates GaAs-AlGaAs-GaAs NWs fabricated by self-catalyzed growth on Si substrates, and partially covered with gold, thus inducing the symmetry breaking and a potential chiral response. Three different samples are investigated, each of them with a different morphology, as the length and the overall diameter ranging from 4.6 to 5.19 µm and from 138 up to 165 nm, respectively. The samples are first char...

Despite the near-unity internal quantum efficiencies (IQEs) demonstrated for GaAs based light emitters, laser cooling of the ubiquitous III-V semiconductors has not been feasible. The key challenges for III-V optical cooling are the reduced absorption of the optical excitation at photon energies well below the band gap and the strong confinement of the light in the high refractive index semiconductors. Here we investigate the possibility to eliminate the need for light extraction and to eventually relax the requirements of the IQE. This is done by using electroluminescence and optical energy transfer within intracavity devices consisting of an AlGaAs/GaAs double heterojunction LED and a GaAs pn-homojunction photodiode enclosed within a single semiconductor cavity. We measure the intracavity energy transfer i.e. the coupling quantum efficiency (CQE) between the two diodes and estimate loss mechanisms by simultaneously measuring the IV-characteristics of the emitter diode and the photocurrent of the absorber diode. The measured CQE is below 60 % due to the mirror, light extraction, nonradiative and detection losses. While this is far below the state-of-the-art efficiencies, our results suggest that it will be possible to substantially improve the efficiency by adopting the fabrication and design principles used for the best performing photoluminescent emitters.

Tellurium (Te)-doping of self-catalyzed GaAs nanowires (NWs) grown by molecular beam epitaxy is reported. The effect of Te-doping on the morphological and crystal structure of the NWs is investigated by scanning electron microscopy and high-resolution transmission electron microscopy. The study reveals that the lateral growth rate increases and axial growth rate decreases with increasing Te doping level. The changes in the NW morphology can be reverted to some extent by changing the growth temperature. At high doping levels, formation of twinning superlattice is observed alongside with the {111}-facetted sidewalls. Finally, the incorporation of Te is confirmed by Raman spectroscopy. V

We report self-catalyzed growth of GaAs nanowires (NWs) on Si/SiOx patterns fabricated by a lithography-free method. The patterns are defined using droplet epitaxy of GaAs nanocrystals, spontaneous oxidation, and thermal annealing. We investigate the influence of the size and density of the nucleation sites on the NW growth process and show that this approach enables the fabrication of highly uniform GaAs NWs with controllable density. The pattern fabrication and NW growth process are studied and discussed in relation to the surface morphology and chemical properties of the Si/SiOx patterns. Furthermore, the optical quality of the NWs is investigated by photoluminescence experiments performed for GaAs–AlGaAs core–shell NWs.