Sharp-line photoluminescence of excitons localized at GaAs/AlGaAs quantum well inhomogeneities

Brunner, K.; Abstreiter, G.; Böhm, G.; Tränkle, G.; Weimann, G.

doi:10.1063/1.111265

Cited by 130 publications

(61 citation statements)

References 12 publications

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“…This weaker contribution would only be effective along the NW growth axis and not along the NW circumference and on its own is not sufficient to achieve the observed full three-dimensional confinement. The such formed 'natural', interface fluctuation QDs have been studied over the past in type-I, direct bandgap GaAs/AlGaAs QWs [37,38,39,40] as well as in type-II, indirect bandgap GaAs/AlAs QWs [41]. The superior optical quality of this type of QDs manifests itself in long exciton coherence times [42] and clean single photon emission [43].…”

Section: Sample and Optical Characterizationmentioning

confidence: 99%

Radio frequency occupancy state control of a single nanowire quantum dot

Weiß¹,

Schülein²,

Kinzel³

et al. 2014

J. Phys. D: Appl. Phys.

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Abstract.The excitonic occupancy state of a single, nanowire-based, heterostructure quantum dot is dynamically programmed by a surface acoustic wave. The quantum dot is formed by an interface or thickness fluctuation of a GaAs QW embedded in a AlGaAs shell of a GaAs − AlGaAs core-shell nanowire. As we tune the time at which carriers are photogenerated during the acoustic cycle, we find pronounced intensity oscillations of neutral and negatively charged excitons. At high acoustic power levels these oscillations become anticorrelated which enables direct acoustic programming of the dot's charge configuration, emission intensity and emission wavelength. Numerical simulations confirm that the observed modulations arise from acoustically controlled modulations of the electron and electron-hole-pair concentrations at the position of the quantum dot.

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Section: Sample and Optical Characterizationmentioning

confidence: 99%

Radio frequency occupancy state control of a single nanowire quantum dot

Weiß¹,

Schülein²,

Kinzel³

et al. 2014

J. Phys. D: Appl. Phys.

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“…The observation of microroughness on top of the macroscopically flat islands gives support to this model. 10 Additionally, PL with spatial resolution 11,12 and near-field spectroscopy 13 showed that the PL line shape is composed by the superposition of many very narrow lines ͑some eV wide͒ that are associated with excitons localization by different lateral-potential fluctuations. Then, the farfield spectrum, i.e., the traditionally observed PL spectrum, is interpreted as an envelope of the very narrow lines associated with defects of different sizes.…”

mentioning

confidence: 99%

“…11 In this sense the lateral dimension ␦ 2 extracted from the Singh and Bajaj equation has to be interpreted as an effective lateral-interface-microroughness size.…”

mentioning

confidence: 99%

Magneto-optical studies of the correlation between interface microroughness parameters and the photoluminescence line shape inGaAs/Ga0.7Al0.3
Oliveira
¹
,
Menêses
²
,
Silva
³

1999
Phys. Rev. B
18
1
4
0
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In this work we analyze the relation between the interface microroughness and the full width at half maximum ͑FWHM͒ of the photoluminescence ͑PL͒ spectra for a GaAs/Ga 0.7 Al 0.3 As multiple quantum well ͑QW͒ system. We show that, in spite of the complex correlation between the microscopic interface-defects parameters and the QW optical properties, the Singh and Bajaj model ͓Appl. Phys. Lett. 44, 805 ͑1984͔͒ provides a good quantitative description of the excitonic PL-FWHM. ͓S0163-1829͑99͒01424-1͔The interfaces structural properties in quantum wells ͑QW's͒ have been extensively investigated, as they are extremely important for the high performance of the electronic and optoelectronic QW-based devices. [1][2][3] Semiconductor heterostructures interfaces have been investigated by means of direct or indirect characterization techniques. Direct investigations of the interfacial quality have been obtained, for instance, by scanning tunneling microscopy, atomic force microscopy, and transmission electron microscopy ͑TEM͒. 4 However, interfaces that are deep inside a semiconductor heterostructure are not accessible through direct investigation methods, so optical techniques ͑which indirectly probe the interfaces͒ have been intensively used in semiconductor-interface characterization in QW systems.One of the most efficient sensors used in the optical characterization of interfacial quality, due to their sensitivity to the structural aspects of the interface on the atomic scale, is the behavior of confined excitons. 5 In fact, an interesting subject of debate is the correlation between the excitonic optical properties and the microscopic configurations of the interfaces. [6][7][8] The flat island model ͑FIM͒ associates the properties of the QW emission lines with the microscopic patterns of the interfaces. According to this model, when the excitons are confined in extensive and plane islands, which have larger dimensions than the exciton lateral dimension, the photoluminescence ͑PL͒ emission line splits. These splittings are due to different confinement potentials, which are associated with islands of different sizes. Moreover, each one of the split PL emission line is broadened due to confinementpotential fluctuations. These fluctuations are due to interface microroughness ͑defects with smaller extension than that of the lateral dimension of the confined exciton͒ and to alloy fluctuations, resulting in an inhomogeneous ͑Gaussian͒ broadening of the PL spectrum. In addition, the emission spectra are also broadened due to final-state interactions ͑Lorentzian broadening͒ and due to the thermal distribution of the carriers.In the FIM, the QW has different widths that differ from each other by an integer multiple of monolayers ͑ML͒, resulting in several PL peaks with corresponding differences in energy. However, more recently, splittings in the PL spectra related to noninteger ML variations in the QW width were observed. 9 The authors of Ref. 9 argued that for a realistic description of the interfaces it is necessary to use a...

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“…(12)) diverges when the energy of the intermediate state coincides with the initial or final state. To remove this divergence, we take into account the finite lifetime of the intermediate level and add a small broadening parameter (an order-of-magnitude estimate is 0.1meV 16,17,18 ) to the energy of the intermediate state to convert this divergence into a resonance near the degeneracy point. 19 This broadening parameter is not crucial for our calculation and would not change the qualitative behavior of the SFR.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

Spin relaxation in diluted magnetic semiconductor quantum dots

Yang

Chang

2005

Phys. Rev. B

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Electron spin relaxation induced by phonon-mediated s-d exchange interaction in a II-VI diluted magnetic semiconductor quantum dot is investigated theoretically. The electron-acoustic phonon interaction due to piezoelectric coupling and deformation potential is included. The resulting spin lifetime is typically on the order of microseconds. The effectiveness of the phonon-mediated spinflip mechanism increases with increasing Mn concentration, electron spin splitting, vertical confining strength and lateral diameter, while it shows non-monotonic dependence on the magnetic field and temperature. An interesting finding is that the spin relaxation in a small quantum dot is suppressed for strong magnetic field and low Mn concentration at low temperature.

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Sharp-line photoluminescence of excitons localized at GaAs/AlGaAs quantum well inhomogeneities

Cited by 130 publications

References 12 publications

Radio frequency occupancy state control of a single nanowire quantum dot

Radio frequency occupancy state control of a single nanowire quantum dot

Magneto-optical studies of the correlation between interface microroughness parameters and the photoluminescence line shape inGaAs/Ga0.7Al0.3
Oliveira
¹
,
Menêses
²
,
Silva
³

1999
Phys. Rev. B
18
1
4
0
View full text Add to dashboard Cite

Spin relaxation in diluted magnetic semiconductor quantum dots

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Sharp-line photoluminescence of excitons localized at GaAs/AlGaAs quantum well inhomogeneities

Cited by 130 publications

References 12 publications

Radio frequency occupancy state control of a single nanowire quantum dot

Radio frequency occupancy state control of a single nanowire quantum dot

Magneto-optical studies of the correlation between interface microroughness parameters and the photoluminescence line shape inGaAs/Ga0.7Al0.3Oliveira1, Menêses2, Silva3 1999Phys. Rev. B18140View full textAdd to dashboardCite

Spin relaxation in diluted magnetic semiconductor quantum dots

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About

Magneto-optical studies of the correlation between interface microroughness parameters and the photoluminescence line shape inGaAs/Ga0.7Al0.3
Oliveira
¹
,
Menêses
²
,
Silva
³

1999
Phys. Rev. B
18
1
4
0
View full text Add to dashboard Cite