Search results for "Wire"
showing 10 items of 1383 documents
Resonant Raman scattering of core-shell GaN/AlN nanowires.
2020
Abstract We have analyzed the electron–phonon coupling in GaN/AlN core–shell nanowires by means of Raman scattering excited at various wavelengths in the ultraviolet spectral range (335, 325 and 300 nm) and as a function of the AlN shell thickness. The detailed analysis of the multi-phonon spectra evidences important differences with excitation energy. Under 325 and 300 nm excitation the Raman process is mediated by the allowed A 1(LO) phonon mode, where the atoms vibrate along the NW axis. Considering its selection rules, this mode is easily accessible in backscattering along the wurtzite c axis. Interestingly, for 335 nm excitation the scattering process is instead mediated by the E 1(LO)…
Photoconductive properties of Bi2S3nanowires
2015
The photoconductive properties of Bi2S3 nanowires synthesized inside anodized alumina (AAO) membrane have been characterized as a function of illuminating photon energy between the wavelengths of 500 to 900 nm and at constant illumination intensity of 1–4 μW·cm−2. Photoconductivity spectra, photocurrent values, photocurrent onset/decay times of individual Bi2S3 nanowires liberated from the AAO membrane were determined and compared with those of arrays of as-produced Bi2S3 nanowires templated inside pores of AAO membrane. The alumina membrane was found to significantly influence the photoconductive properties of the AAO-hosted Bi2S3 nanowires, when compared to liberated from the AAO membrane…
Size-filtering effects by stacking InAs/InP (001) self-assembled quantum wires into multilayers
2002
Multilayer structure containing vertically stacked InAs/InP self-assembled quantum wires have been successfully grown by molecular-beam epitaxy. The influence of the InP spacer layer thickness on the structural and optical properties of the wire superlattice has been studied by means of transmission electron microscopy and photoluminescence. The coherent propagation of the strain field in the sample with a 5-nm-thick spacer determines by a size filtering effect a good homogeneity and uniformity of the wire stacks, and hence a good optical quality. The exciton recombination dynamics in the wire superlattice cannot be related to thermal escape of carriers out to the barriers, as occurs in sin…
Size self-filtering effect in vertical stacks of InAs/InP self-assembled quantum wires
2003
3 páginas, 2 figuras.-- PACS: 73.21.Hb; 78.55.Cr; 78.67.Lt.-- Proceedings of the International Conference on Superlattices, Nano-structures and Nano-devices ICSNN 2002.
Defect spectroscopy of single ZnO microwires
2014
The point defects of single ZnO microwires grown by carbothermal reduction were studied by microphotoluminescence, photoresistance excitation spectra, and resistance as a function of the temperature. We found the deep level defect density profile along the microwire showing that the concentration of defects decreases from the base to the tip of the microwires and this effect correlates with a band gap narrowing. The results show a characteristic deep defect levels inside the gap at 0.88 eV from the top of the VB. The resistance as a function of the temperature shows defect levels next to the bottom of the CB at 110 meV and a mean defect concentration of 4 1018 cm3 . This combination of tech…
Ultrathin silicon nanowires for optical and electrical nitrogen dioxide detection
2021
The ever-stronger attention paid to enhancing safety in the workplace has led to novel sensor development and improvement. Despite the technological progress, nanostructured sensors are not being commercially transferred due to expensive and non-microelectronic compatible materials and processing approaches. In this paper, the realization of a cost-effective sensor based on ultrathin silicon nanowires (Si NWs) for the detection of nitrogen dioxide (NO2) is reported. A modification of the metal-assisted chemical etching method allows light-emitting silicon nanowires to be obtained through a fast, low-cost, and industrially compatible approach. NO2 is a well-known dangerous gas that, even wit…
Non-resonant Raman spectroscopy of individual ZnO nanowires via Au nanorod surface plasmons
2016
We present a non-resonant Raman spectroscopy study of individual ZnO nanowires mediated by Au nanorod surface plasmons. In this approach, selective excitation of the plasmonic oscillations with radiation energy below the semiconductor bandgap was used to probe surface optical modes of individual ZnO nanowires without simultaneous excitation of bulk phonons modes or band-edge photoluminescence. The development of a reproducible method for decoration of nanowires with colloidal Au nanorods allowed performing an extensive statistical analysis addressing the variability and reproducibility of the Raman features found in the hybrid nanostructures. An estimated field enhancement factor of 103 was…
Spatial Distribution of the Nonlinear Photoluminescence in Au Nanowires
2019
When gold nanowires are excited with a tightly focused femtosecond laser a distributed nonlinear photoluminescence (N-PL) develops throughout the entire structure. A complete spaced-resolved analysis of the spectral signature of the nanowire nonlinear response is carried out to understand the origin of the distributed nonlinear response. We discuss various mechanisms to explain the experimental data and unambiguously demonstrate that the spatial and spectral extension of the N-PL in the nanowire are mainly dictated by the propagation of a surface plasmon excited at the pump wavelength. We also present experimental signature of near-field excitation of a broadband continuum of surface plasmo…
Polarized recombination of acoustically transported carriers in GaAs nanowires
2012
: The oscillating piezoelectric field of a surface acoustic wave (SAW) is employed to transport photoexcited electrons and holes in GaAs nanowires deposited on a SAW delay line on a LiNbO3 crystal. The carriers generated in the nanowire by a focused light spot are acoustically transferred to a second location where they recombine. We show that the recombination of the transported carriers occurs in a zinc blende section on top of the predominant wurtzite nanowire. This allows contactless control of the linear polarized emission by SAWs which is governed by the crystal structure. Additional polarization-resolved photoluminescence measurements were performed to investigate spin conservation d…
Unexpected Epitaxial Growth of a Few WS2 Layers on {11̅00} Facets of ZnO Nanowires
2016
Core–shell nanowires are an interesting and perspective class of radially heterostructured nanomaterials where epitaxial growth of the shell can be realized even at noticeable core–shell lattice mismatch. In this study epitaxial hexagonally shaped shell consisting of WS2 nanolayers was grown on {1100} facets of prismatic wurtzite-structured [0001]-oriented ZnO nanowires for the first time. A synthesis was performed by annealing in a sulfur atmosphere of ZnO/WO3 core–shell structures, produced by reactive dc magnetron sputtering of an amorphous a-WO3 layer on top of ZnO nanowire array. The morphology and phase composition of synthesized ZnO/WS2 core–shell nanowires were confirmed by scanning…