scholarly journals Polarization Anisotropies in Strain-Free, Asymmetric and Symmetric Quantum Dots Grown by Droplet Epitaxy

2021 ◽  
Author(s):  
Marco Abbarchi ◽  
takaaki mano ◽  
takashi kuroda ◽  
kazuaki sakoda
Keyword(s):  
Quantum Dots ◽  
Systematic Investigation ◽  
Binding Energies ◽  
Droplet Epitaxy ◽  
Wetting Layer ◽  
Symmetric Quantum ◽  
Order Of Magnitude ◽  
Structure Splitting ◽  
Charged Exciton ◽  
Further Development

We provide an extensive and systematic investigation of exciton dynamics in droplet epitaxial quantum dots comparing the cases of (311)A, (001) and (111)A surfaces. In spite of a similar s-shell exciton structure common to the three cases, the absence of a wetting layer for (311)A and (111)A samples leads to a larger carrier confinement with respect to (001), where a wetting layer is present. Moreover, this leads to a more pronounced dependence of the binding energies of s-shell excitons on the quantum dot size and to a strong anti-binding character of the positive charged exciton for smaller quantum dots. In-plane geometrical anisotropies of (311)A and (001) quantum dots lead to a large electron-hole fine interaction (fine structure splitting, FSS ~ 100 ueV) whereas for the three-fold symmetric (111)A counterpart this figure of merit is reduced of about one order of magnitude. In all these cases we do not observe any size dependence of the fine interactions. Heavy-hole/light-hole mixing is present in all the studied cases leading to a broad spread of linear polarization anisotropy (from 0 up to about 50%) irrespective of surface orientation (symmetry of the confinement), fine interactions and nanostructure size. These results are important for the further development of ideal single and entangled photon sources based on semiconductor quantum dots.

scholarly journals Polarization Anisotropies in Strain-Free, Asymmetric, and Symmetric Quantum Dots Grown by Droplet Epitaxy

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 443
Author(s):  
Marco Abbarchi ◽  
Takaaki Mano ◽  
Takashi Kuroda ◽  
Akihiro Ohtake ◽  
Kazuaki Sakoda
Keyword(s):  
Quantum Dots ◽  
Fine Structure ◽  
Systematic Investigation ◽  
Binding Energies ◽  
Droplet Epitaxy ◽  
Wetting Layer ◽  
Fine Structure Splitting ◽  
Symmetric Quantum ◽  
Order Of Magnitude ◽  
Structure Splitting

We provide an extensive and systematic investigation of exciton dynamics in droplet epitaxial quantum dots comparing the cases of (311)A, (001), and (111)A surfaces. Despite a similar s-shell exciton structure common to the three cases, the absence of a wetting layer for (311)A and (111)A samples leads to a larger carrier confinement compared to (001), where a wetting layer is present. This leads to a more pronounced dependence of the binding energies of s-shell excitons on the quantum dot size and to the strong anti-binding character of the positive-charged exciton for smaller quantum dots. In-plane geometrical anisotropies of (311)A and (001) quantum dots lead to a large electron-hole fine interaction (fine structure splitting (FSS) ∼100 μeV), whereas for the three-fold symmetric (111)A counterpart, this figure of merit is reduced by about one order of magnitude. In all these cases, we do not observe any size dependence of the fine structure splitting. Heavy-hole/light-hole mixing is present in all the studied cases, leading to a broad spread of linear polarization anisotropy (from 0 up to about 50%) irrespective of surface orientation (symmetry of the confinement), fine structure splitting, and nanostructure size. These results are important for the further development of ideal single and entangled photon sources based on semiconductor quantum dots.

Size-dependent binding energies and fine-structure splitting of excitonic complexes in single InAs/GaAs quantum dots

2007 ◽  
Vol 122-123 ◽  
pp. 735-739 ◽  
Author(s):  
S. Rodt ◽  
R. Seguin ◽  
A. Schliwa ◽  
F. Guffarth ◽  
K. Pötschke ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Fine Structure ◽  
Binding Energies ◽  
Size Dependent ◽  
Fine Structure Splitting ◽  
Structure Splitting

Modified droplet epitaxy GaAs/AlGaAs quantum dots grown on a variable thickness wetting layer

2003 ◽  
Vol 253 (1-4) ◽  
pp. 71-76 ◽  
Author(s):  
S. Sanguinetti ◽  
K. Watanabe ◽  
T. Tateno ◽  
M. Gurioli ◽  
P. Werner ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Variable Thickness ◽  
Droplet Epitaxy ◽  
Wetting Layer

Self-assembled GaAs quantum dots coupled with GaAs wetting layer grown on GaAs (311)A by droplet epitaxy

2010 ◽  
Vol 8 (2) ◽  
pp. 257-259 ◽  
Author(s):  
Takaaki Mano ◽  
Takeshi Noda ◽  
Takashi Kuroda ◽  
Stefano Sanguinetti ◽  
Kazuaki Sakoda
Keyword(s):  
Quantum Dots ◽  
Droplet Epitaxy ◽  
Wetting Layer ◽  
Self Assembled

EFFECTS OF ANTIMONY FLUX ON MORPHOLOGY AND PHOTOLUMINESCENCE SPECTRA OF GaSb QUANTUM DOTS FORMED ON GaAs BY DROPLET EPITAXY

2010 ◽  
Vol 19 (04) ◽  
pp. 819-826 ◽  
Author(s):  
T. KAWAZU ◽  
T. NODA ◽  
T. MANO ◽  
M. JO ◽  
H. SAKAKI
Keyword(s):  
Quantum Dots ◽  
Microscope Study ◽  
Molecular Beam ◽  
Broad Peak ◽  
Droplet Epitaxy ◽  
Wetting Layer ◽  
Photoluminescence Spectra ◽  
Coalescence Process ◽  
Strong Luminescence

We investigated effects of the antimony flux on GaSb quantum dots (QDs) formed by droplet epitaxy. Ga droplets were first formed on GaAs and exposed to Sb4 molecular beam at 200 °C, where the flux PSb of Sb beam was varied from 2.4 to 12.8 × 10-7 Torr. The samples were then annealed for 2 minutes under the Sb flux. An atomic microscope study showed that the diameter of GaSb QDs increases and the density decreases, as the Sb flux PSb is increased. This indicates that the coalescence process of GaSb QDs occurs and is accelerated by the increase of the Sb flux. In a photoluminescence (PL) study, we observed a broad peak of GaSb QDs in all samples, while a strong luminescence of a wetting layer (WL)-like structure was found only in the samples prepared with the high Sb flux. This suggests that the PL of WL is controllable by adjusting the flux PSb of Sb beam.

scholarly journals Exciton Dynamics in Droplet Epitaxial Quantum Dots Grown on (311)A Oriented Substrates

2020 ◽  
Author(s):  
Marco Abbarchi ◽  
Takaaki Mano ◽  
Takashi Kuroda ◽  
Kazuaki Sakoda
Keyword(s):  
Quantum Dots ◽  
Heavy Hole ◽  
Single Photon ◽  
Light Hole ◽  
Droplet Epitaxy ◽  
Wetting Layer ◽  
Phonon Interaction ◽  
Optical And Electronic Properties ◽  
Higher Temperature ◽  
Quantum Emitters

Droplet epitaxy allows the efficient fabrication of a plethora of 3D, III-V-based nanostructures on different crystalline orientations. Quantum dots grown on (311)A-oriented surface are obtained with record surface density, with or without a wetting layer. These are appealing features for quantum-dot lasing, thanks to the large density of quantum emitters and a truly 3D lateral confinement. However, the intimate photophysics of this class of nanostructures has not yet been investigated. Here we address the main optical and electronic properties of s-shell excitons in individual quantum dots grown on (311)A substrates with photoluminescence spectroscopy experiments. We show the presence of neutral exciton and biexciton as well as positive and negative charged excitons. We investigate the origins of spectral broadening, identifying them in spectral diffusion at low temperature and phonon-interaction at higher temperature, the presence of fine interactions between electron and hole spin, and a relevant heavy-hole/light-hole mixing. We interpret the level filling with a simple Poissonian model reproducing the power excitation dependence of the s-shell excitons. These results are relevant for the further improvement of this class of quantum emitters and their exploitation as single photon sources for low density samples as well as for efficient lasers for high density samples.

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