| 1. |
- Jansson, Mattias, et al.
(författare)
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High-Performance Multiwavelength GaNAs Single Nanowire Lasers
- 2024
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Ingår i: ACS Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 18:2, s. 1477-1484
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we report a significant enhancement in the performance of GaNAs-based single nanowire lasers through optimization of growth conditions, leading to a lower lasing threshold and higher operation temperatures. Our analysis reveals that these improvements in the laser performance can be attributed to a decrease in the density of localized states within the material. Furthermore, we demonstrate that owing to their excellent nonlinear optical properties, these nanowires support self-frequency conversion of the stimulated emission through second harmonic generation (SHG) and sum-frequency generation (SFG), providing coherent light emission in the cyan-green range. Mode-specific differences in the self-conversion efficiency are revealed and explained by differences in the light extraction efficiency of the converted light caused by the electric field distribution of the fundamental modes. Our work, therefore, facilitates the design and development of multiwavelength coherent light generation and higher-temperature operation of GaNAs nanowire lasers, which will be useful in the fields of optical communications, sensing, and nanophotonics.
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| 2. |
- Jansson, Mattias, et al.
(författare)
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Lattice dynamics and carrier recombination in GaAs/GaAsBi nanowires
- 2023
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Ingår i: Scientific Reports. - : NATURE PORTFOLIO. - 2045-2322. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- GaAsBi nanowires represent a novel and promising material platform for future nano-photonics. However, the growth of high-quality GaAsBi nanowires and GaAsBi alloy is still a challenge due to a large miscibility gap between GaAs and GaBi. In this work we investigate effects of Bi incorporation on lattice dynamics and carrier recombination processes in GaAs/GaAsBi core/shell nanowires grown by molecular-beam epitaxy. By employing photoluminescence (PL), PL excitation, and Raman scattering spectroscopies complemented by scanning electron microscopy, we show that increasing Bi-beam equivalent pressure (BEP) during the growth does not necessarily result in a higher alloy composition but largely affects the carrier localization in GaAsBi. Specifically, it is found that under high BEP, bismuth tends either to be expelled from a nanowire shell towards its surface or to form larger clusters within the GaAsBi shell. Due to these two processes the bandgap of the Bi-containing shell remains practically independent of the Bi BEP, while the emission spectra of the NWs experience a significant red shift under increased Bi supply as a result of the localization effect.
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| 3. |
- Lemishko, S. V., et al.
(författare)
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Dielectric resonator in rectangular ??(102) cavity for electron paramagnetic resonance study of thin films
- 2023
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Ingår i: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 768
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Tidskriftsartikel (refereegranskat)abstract
- The improved compared to a rectangular TE(102 )cavity geometry of a dielectric resonator (DR) suitable for studying thin films and coatings has been calculated and experimentally verified. It is shown that electron paramagnetic resonance (EPR) signal of SiOx films can be enhanced by using as the DR of two rectangular parallelepipeds fabricated from BaTi4O9 + 8.5% ZnO ceramics (epsilon=36) with dimension of 5.64x5.5 x 5.9 mm(3 )and a gap of up to 0.5 mm between them. Located inside a standard rectangular metal TE(102 )cavity of the X-band EPR spectrometer, the DR increases the filling factor by 5-12 times depending on the size of a sample studied. The experimental use of the DR allows to increase the EPR signal of the 950 nm SiOx thin film by a factor of approximately 4.
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| 4. |
- Vorona, Igor, 1967-, et al.
(författare)
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Size-Dependent Effects in Optically Detected Magnetic Resonance Spectra of CdS Nanocrystals
- 2022
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 126:36, s. 15465-15471
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Tidskriftsartikel (refereegranskat)abstract
- A quasi-white photoluminescence (PL) emission of colloidal CdS nanocrystals (NCs) of various sizes (2, 3, and 6 nm) embedded in a polymer matrix was examined by optically detected magnetic resonance (ODMR) spectroscopy. The registered ODMR spectra are complex, composed of both positive and negative signals. The positive component of the ODMR signal depends strongly on both particle size and the range of the PL wavelength registration. Based on this behavior it is ascribed to the complex paramagnetic centers formed by electron-and hole-trapping species coupled by an exchange interaction. By variation of the state of the NC/polymer interface, it is shown that the electron-trapping center is located at the interface. The sharp negative component of the ODMR spectra does not depend on the NC size. It was assigned to a sulfur vacancy (V-s) acting as a center of nonradiative recombination.
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