Excitons in InGaAs quantum dots without electron wetting layer states

Abstract

The Stranski-Krastanov (SK) growth-mode facilitates the self-assembly of quantum dots (QDs) using lattice-mismatched semiconductors, for instance InAs and GaAs. SK QDs are defect-free and can be embedded in heterostructures and nano-engineered devices. InAs QDs are excellent photon emitters: QD-excitons, electron-hole bound pairs, are exploited as emitters of high quality single photons for quantum communication. One significant drawback of the SK-mode is the wetting layer (WL). The WL results in a continuum rather close in energy to the QD-confined-states. The WL-states lead to unwanted scattering and dephasing processes of QD-excitons. Here, we report that a slight modification to the SK-growth-protocol of InAs on GaAs -we add a monolayer of AlAs following InAs QD formation -results in a radical change to the QD-excitons. Extensive characterisation demonstrates that this additional layer eliminates the WL-continuum for electrons enabling the creation of highly charged excitons where up to six electrons occupy the same QD. Single QDs grown with this protocol exhibit optical linewidths matching those of the very best SK QDs making them an attractive alternative to standard InGaAs QDs. arXiv:1810.00891v1 [cond-mat.mes-hall]

Vanishing fine structure splitting in highly asymmetric InAs/InP quantum dots without wetting layer

“…Such approach combined with decoupling of the wetting layer from quantum dash spectra could be beneficial for tailoring of low BES system, similar to tailoring number of charged excitons in systems without the wetting layer. 67…”

“…Apart from approaches based on droplet epitaxy 65 , 66 , obtaining such nanostructures seems at first very unlikely in the Stransky-Krastanov growth mode. However, recently an effective decoupling of the wetting layer from the quantum dot has been achieved by the addition of a monolayer of AlAs following the InAs quantum dot formation 67 . Ref.…”

“…Ref. 67 thus opens possibilities of obtaining Stransky-Krastanov assembled nanostructures with highly limited role of the wetting layer. Following these recent experimental efforts, we exploit such concept theoretically in this paper, by considering elongated quantum dot systems, yet grown without the wetting layer, conceivably with prospects of experimental realization of such quantum dots-quantum dash structures in near future.…”

Quantum Confined Stark Effect on the Linear and Nonlinear Optical Properties of SiGe/Si Semi Oblate and Prolate Quantum Dots Grown in Si Wetting Layer

“…However, during the growth process, the constraints generated by lattice mismatch of different materials and the strain of WL cause non-symmetrical and non-homogenous shapes. Thus, different shapes with different size dispersions can be observed by TEM imaging: hemispherical, disk, cylinder, lens, ring, conical, pyramidal, dome, oblate and prolate or semi oblate and prolate [11][12][13][14][15][16][17][18][19][20].…”

Исследование оптических и структурных свойств трехмерных островков InGaP(As), сформированных методом замещения элементов пятой группы

“…В настоящее время большой интерес проявляется к созданию приборов для управления одиночными фотонами [1][2][3][4][5][6][7][8][9] и нейроморфных вычислений, использующих в качестве излучателей полупроводниковые гетероструктуры с пониженной размерностью [10][11][12]. Наилучшими кандидатами на роль активных областей для излучателей в таких системах являются квантовые точки (КТ).…”