Droplet epitaxy quantum dot based infrared photodetectors

Vichi, Stefano; Bietti, Sergio; Khalili, Arastoo; Costanzo, Matteo; Cappelluti, Federica; Esposito, Luca; Somaschini, Claudio; Fedorov, Alexey; Tsukamoto, Shiro; Rauter, Patrick; Sanguinetti, S.

doi:10.1088/1361-6528/ab7aa6

Cited by 13 publications

(15 citation statements)

References 38 publications

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“…Nonetheless, very recent studies on InAs/InP QDs have evidenced the role of CI even for isotropic QDs [32]. For the particular system, InAs/InP elongated along the [1][2][3][4][5][6][7][8][9][10] axis with strain and a small volume (h QD = 3 nm and √ r 0x r 0y = 20 nm), CI has a vanishing effect on δ DD for β < 4 (t = 0 − 0.9 in Ref. [32]), while for β = 4, δ BB and δ BD can be increased by up to 80% and 40%, respectively.…”

Section: Resultsmentioning

confidence: 94%

“…(iii) effects due to the zinc-blende symmetry and nonequivalent [110] and [1][2][3][4][5][6][7][8][9][10] axes [42];…”

Section: Resultsmentioning

confidence: 99%

“…In conventional semiconductors, like GaAs, neutral excitons are splitted in two kinds of states, optically active [bright exciton (BE)] or inactive [dark exciton (DE)]. The BEs have been extensively studied in the last decades because they are decisive for optoelectronic applications based on QDs [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Fine structure of bright and dark excitons in asymmetric droplet epitaxy GaAs/AlGaAs quantum dots

et al. 2021

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We have calculated the exciton fine structure splittings (FSS) of asymmetric GaAs/AlGaAs quantum dots (QDs) obtained after Al droplet epitaxy and subsequent nanoholes formation followed by annealing and GaAs filling of nanoholes. We used a k • p model and considered the heavy-hole and light-hole mixing to calculate the electron-hole exchange interaction (EI). The two components, long-range (LR) and short-range (SR) of the EI, were deduced. The exciton fine structure is organized, as usual in zinc-blende compounds, into two groups of states: bright (optically active) and dark states. The bright-dark and bright-bright splittings contain LR and SR contributions, the LR part representing 5 to 68% of the total bright-dark splitting and 69 to 76% of the total bright-bright splitting for sizes experimentally explored. In QDs having C 2v symmetry, LR and SR contributions to dark-dark splitting have to be calculated at the second order of perturbation theory. A good agreement between the theory and experiment is obtained for QDs with different degrees of asymmetry, from QD having an isotropic shape to QD with a very anisotropic shape.

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Section: Resultsmentioning

confidence: 94%

“…(iii) effects due to the zinc-blende symmetry and nonequivalent [110] and [1][2][3][4][5][6][7][8][9][10] axes [42];…”

Section: Resultsmentioning

confidence: 99%

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Fine structure of bright and dark excitons in asymmetric droplet epitaxy GaAs/AlGaAs quantum dots

et al. 2021

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“…Droplet epitaxy [1][2][3][4] and droplet etching [5][6][7][8][9][10][11][12][13] (DE) are alternative growth protocols to Stranski-Krastanov for the fabrication of strain-free III-V-based semiconductor quantum dots (QDs). This emerging class of nanostructures has been efficiently exploited for the fabrication of classical optoelectronic devices such as photodetectors [14], lasers [15][16][17][18][19], and quantum emitters [13,[20][21][22][23][24][25][26][27][28][29][30][31][32], demonstrating the relevance of this approach for realistic applications.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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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.

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“…Droplet epitaxy (DE) is a well-established method for producing quantum dots (QDs) with an independent control of nanostructure size and its density in the wide range [ 1 , 2 ]. Using DE, it is possible to fabricate low-density QDs for quantum emitters [ 1 , 2 , 3 , 4 ] or high-density nanostructures for laser and photodetector devices [ 5 , 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

Reentrant Behavior of the Density vs. Temperature of Indium Islands on GaAs(111)A

et al. 2020

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We show that the density of indium islands on GaAs(111)A substrates have a non-monotonic, reentrant behavior as a function of the indium deposition temperature. The expected increase in the density with decreasing temperature, indeed, is observed only down to 160 ∘C, where the indium islands undertake the expected liquid-to-solid phase transition. Further decreasing the temperature causes a sizable reduction of the island density. An additional reentrant increasing behavior is observed below 80 ∘C. We attribute the above complex behavior to the liquid–solid phase transition and to the complex island–island interaction which takes place between crystalline islands in the presence of strain. Indium solid islands grown at temperatures below 160 ∘C have a face-centered cubic crystal structure.

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Droplet epitaxy quantum dot based infrared photodetectors

Cited by 13 publications

References 38 publications

Fine structure of bright and dark excitons in asymmetric droplet epitaxy GaAs/AlGaAs quantum dots

Fine structure of bright and dark excitons in asymmetric droplet epitaxy GaAs/AlGaAs quantum dots

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

Reentrant Behavior of the Density vs. Temperature of Indium Islands on GaAs(111)A

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