| 1. |
- Girshova, E. I, et al.
(författare)
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Enhancement of the Basal-plane Stacking Fault Emission in GaN Planar Nanowire Microcavity
- 2022
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Ingår i: JETP Letters. - : MAIK NAUKA/INTERPERIODICA/SPRINGER. - 0021-3640 .- 1090-6487. ; 115, s. 574-580
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Tidskriftsartikel (refereegranskat)abstract
- We study and compare optical microcavities formed by GaN planar nanowires. Nanostructures with structural defects such as stacking faults and without defects are considered. The behavior of an exciton localized in a stacking fault is considered. Different behavior of the photoluminescence intensity and the photoluminescence decay time is observed for the cases under consideration. Theoretical calculations show the localization of the field at the ends of the structure.
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| 2. |
- Belonovskii, A. V., et al.
(författare)
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Strong Coupling of Excitons in Hexagonal GaN Microcavities
- 2020
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Ingår i: Semiconductors (Woodbury, N.Y.). - : PLEIADES PUBLISHING INC. - 1063-7826 .- 1090-6479. ; 54:1, s. 127-130
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Tidskriftsartikel (refereegranskat)abstract
- The GaN planar hexagonal microcavities are grown by the selective vapor-phase epitaxy technique. The spectra are measured by the low-temperature cathodoluminescence method using a scanning electron microscope. The obtained spectra show a huge Rabi splitting (similar to 100 meV). Numerical simulation of the spatial distribution of the intensities of modes in a hexagonal cavity is carried out. Certain modes can have a high spatial localization leading to strong coupling with the exciton and huge Rabi splitting. The fraction of excitons in polariton modes, which correlates with the intensity of exciton radiation associated with these modes, is theoretically calculated for hexagonal-shaped microcavities. Thus, the form of the dependence of the radiation probability on the eigenfrequencies of the structure is obtained.
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| 3. |
- Pozina, Galia, et al.
(författare)
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Approach to high quality GaN lateral nanowires and planar cavities fabricated by focused ion beam and metal-organic vapor phase epitaxy
- 2018
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a method to fabricate GaN planar nanowires and cavities by combination of Focused Ion Beam (FIB) patterning of the substrate followed by Metal Organic Vapor Phase Epitaxy (MOVPE). The method includes depositing a silicon nitride mask on a sapphire substrate, etching of the trenches in the mask by FIB with a diameter of 40 nm with subsequent MOVPE growth of GaN within trenches. It was observed that the growth rate of GaN is substantially increased due to enhanced bulk diffusion of the growth precursor therefore the model for analysis of the growth rate was developed. The GaN strips fabricated by this method demonstrate effective luminescence properties. The structures demonstrate enhancement of spontaneous emission via formation of Fabry-Perot modes.
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| 4. |
- Pozina, Galia, et al.
(författare)
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Emission Properties of GaN Planar Hexagonal Microcavities
- 2020
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Ingår i: Physica Status Solidi (a) applications and materials science. - : WILEY-V C H VERLAG GMBH. - 1862-6300 .- 1862-6319. ; 217:14
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Tidskriftsartikel (refereegranskat)abstract
- Fabrication of microcavities based on III-nitrides is challenging due to difficulties with the coherent growth of heterostructures having a large number of periods, at the same time keeping a good precision in terms of thickness and composition of the alloy. A planar design for GaN microresonators supporting whispering gallery modes is suggested. GaN hexagonal microstructures are fabricated by selective-area metalorganic vapor phase epitaxy using focused ion beam for mask patterning. Low-temperature cathodoluminescence spectra measured with a high spatial resolution demonstrate two dominant emission lines in the near bandgap region. These lines merge at room temperature into a broad emission band peaking at approximate to 3.3 eV, which is shifted toward lower energies compared with the reference excitonic spectrum measured for the GaN layer. A numerical analysis of exciton-polariton modes shows that some strongly localized cavity modes can have high Purcell coefficients and can strongly interact with the GaN exciton.
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| 5. |
- Pozina, Galia, et al.
(författare)
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Optical Cavity Based on GaN Planar Nanowires Grown by Selective Area Metal-Organic Vapor Phase Epitaxy
- 2019
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Ingår i: Physica status solidi. B, Basic research. - : WILEY-V C H VERLAG GMBH. - 0370-1972 .- 1521-3951. ; 256:6
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Tidskriftsartikel (refereegranskat)abstract
- GaN planar nanowires (NWs) are fabricated by selective area metal-organic vapor phase epitaxy using focused ion beam etching of trench pattern in the Si3N4 mask. Two crystallographic orientations of NWs along [1120] and [1010] directions are investigated. The coherent growth is confirmed for both directions; however, the best morphology, crystalline and optical properties are found in the GaN planar NWs fabricated along the [1010] axis. Cathodoluminescence (CL) at 5K reveals a presence of Fabry-Perot modes in the region of 1.8-2.5 eV for the NWs fabricated in the [1010] direction. The position and intensity of the Fabry-Perot peaks vary depending on measured point within the NW, which is explained by the model based on the Purcell coefficient calculations. It is shown that small fluctuations in the NW thickness cause a noticeable shift of the Fabry-Perot modes energies, while the enhancement or reduction of the emission intensity for the Fabry-Perot peaks depend on the position of the emitter inside the planar NW.
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| 6. |
- Pistol, Mats-Erik, et al.
(författare)
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Random telegraph noise in the photon emission from semiconductor quantum dots
- 2005
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Ingår i: 2005 European Quantum Electronics Conference. - 0780389735 ; , s. 18-18
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Konferensbidrag (refereegranskat)abstract
- This study has observed and investigated random telegraph noise in the photoluminescence from InAs quantum dots in GaAs and InP quantum dots in GaInP. The dots are grown by the Stranski-Krastanow technique with a sufficiently low surface density that individual dots easily could be investigated. The luminescence from many single quantum dots, exhibiting switching between two levels, has been spectrally resolved as a function of time. The random telegraph noise is only observed in the presence of band filling. Results show no spectral shift of the emission in the different states. It is only the intensity, mainly for higher energy peaks that changes. The InAs quantum dots behave very similarly to InP/GaInP and InGaAs/GaAs quantum dots with respect to random telegraph noise. The similarities between the different systems argue for a common mechanism behind the blinking. Experiments are performed where the switching behaviour is changed in all the different systems supporting the idea that non-radiative defects are responsible
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