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| 2. |
- Amloy, Supaluck, et al.
(författare)
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Dynamic characteristics of the exciton and the biexciton in a single InGaN quantum dot
- 2012
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 101:6
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics of the exciton and the biexciton related emission from a single InGaN quantum dot (QD) have been measured by time-resolved microphotoluminescence spectroscopy. An exciton-biexciton pair of the same QD was identified by the combination of power dependence and polarization-resolved spectroscopy. Moreover, the spectral temperature evolution was utilized in order to distinguish the biexciton from a trion. Both the exciton and the biexciton related emission reveal mono-exponential decays corresponding to time constants of similar to 900 and similar to 500 ps, respectively. The obtained lifetime ratio of similar to 1.8 indicates that the QD is small, with a size comparable to the exciton Bohr radius.
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| 3. |
- Amloy, Supaluck, et al.
(författare)
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Excitons and biexcitons in InGaN quantum dot like localization centers
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Indium segregation in a narrow InGaN single quantum well creates quantum dot (QD) like exciton localization centers. Cross section transmission electron microscopy reveals varying shapes and lateral sizes in the range ~1-5 nm of the QD-like features, while scanning near field optical microscopy demonstrates a highly inhomogeneous spatial distribution of optically active individual localization centers. Microphotoluminescence spectroscopy confirms the spectrally inhomogeneous distribution of localization centers, in which the exciton and the biexciton related emissions from single centers of varying geometry could be identified by means of excitation power dependencies. Interestingly, the biexciton binding energy (Ebxx) was found to vary from center to center, between 3 to -22 meV, in correlation with the exciton emission energy. Negative binding energies justify the three-dimensional quantum confinement, which confirms QD-like properties of the localization centers.! The observed energy correlation is proposed to be understood as variations of the lateral extension of the confinement potential, which would yield smaller values of Ebxx for reduced lateral extension and higher exciton emission energy. The proposed relation between lateral extension and Ebxx is further supported by the exciton and the biexciton recombination lifetimes of a single QD, which suggest a lateral extension of merely ~3 nm for a QD with strongly negative Ebxx = -15.5 meV.
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| 4. |
- Amloy, Supaluck, et al.
(författare)
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Excitons and biexcitons in InGaN quantum dot like localization centers
- 2014
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 25:49, s. 495702-
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Tidskriftsartikel (refereegranskat)abstract
- Indium segregation in a narrow InGaN single quantum well creates quantum dot (QD) like exciton localization centers. Cross-section transmission electron microscopy reveals varying shapes and lateral sizes in the range ∼1–5 nm of the QD-like features, while scanning near field optical microscopy demonstrates a highly inhomogeneous spatial distribution of optically active individual localization centers. Microphotoluminescence spectroscopy confirms the spectrally inhomogeneous distribution of localization centers, in which the exciton and the biexciton related emissions from single centers of varying geometry could be identified by means of excitation power dependencies. Interestingly, the biexciton binding energy (Ebxx) was found to vary from center to center, between 3 to −22 meV, in correlation with the exciton emission energy. Negative binding energies are only justified by a three-dimensional quantum confinement, which confirms QD-like properties of the localization centers. The observed energy correlation is proposed to be understood as variations of the lateral extension of the confinement potential, which would yield smaller values of Ebxx for reduced lateral extension and higher exciton emission energy. The proposed relation between lateral extension and Ebxx is further supported by the exciton and the biexciton recombination lifetimes of a single QD, which suggest a lateral extension of merely ∼3 nm for a QD with strongly negative Ebxx = −15.5 meV.
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| 5. |
- Amloy, Supaluck, et al.
(författare)
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Polarization-resolved fine-structure splitting of zero-dimensional InxGa1-xN excitons
- 2011
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Ingår i: PHYSICAL REVIEW B. - : American Physical Society. - 1098-0121. ; 83:20, s. 201307-
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Tidskriftsartikel (refereegranskat)abstract
- The fine-structure splitting of quantum confined InxGa1-x Nexcitons is investigated using polarization-sensitive photoluminescence spectroscopy. The majority of the studied emission lines exhibits mutually orthogonal fine-structure components split by 100-340 mu eV, as measured from the cleaved edge of the sample. The exciton and the biexciton reveal identical magnitudes but reversed sign of the energy splitting.
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| 6. |
- Andersson, J. Y., et al.
(författare)
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Quantum structure based infrared detector research and development within Acreo's centre of excellence IMAGIC
- 2010
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Ingår i: Infrared physics & technology. - : Elsevier BV. - 1350-4495 .- 1879-0275. ; 53:4, s. 227-230
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Tidskriftsartikel (refereegranskat)abstract
- Acreo has a long tradition of working with quantum structure based infrared (IR) detectors and arrays. This includes QWIP (quantum well infrared photodetector), QDIP (quantum dot infrared photodetector), and InAs/GaInSb based photon detectors of different structure and composition. It also covers R&D on uncooled microbolometers. The integrated thermistor material of such detectors is advantageously based on quantum structures that are optimised for high temperature coefficient and low noise. Especially the SiGe material system is preferred due to the compatibility with silicon technology. The R&D work on IR detectors is a prominent part of Acreo's centre of excellence "IMAGIC" on imaging detectors and systems for non-visible wavelengths. IMAGIC is a collaboration between Acreo, several industry partners and universities like the Royal Institute of Technology (KTH) and Linkoping University. (C) 2010 Elsevier B.V. All rights reserved.
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| 8. |
- Dupertuis, M A, et al.
(författare)
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Symmetries and the Polarized Optical Spectra of Exciton Complexes in Quantum Dots
- 2011
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 107:12, s. 127403-
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Tidskriftsartikel (refereegranskat)abstract
- A systematic and simple theoretical approach is proposed to analyze true degeneracies and polarized decay patterns of exciton complexes in semiconductor quantum dots. The results provide reliable spectral signatures for efficient symmetry characterization, and predict original features for low C(2 nu) and high C(3 nu) symmetries. Excellent agreement with single quantum dot spectroscopy of real pyramidal InGaAs/AlGaAs quantum dots grown along [111] is demonstrated. The high sensitivity of biexciton quantum states to exact high symmetry can be turned into an efficient uninvasive postgrowth selection procedure for quantum entanglement applications.
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