The Fine Structure of a Triexciton in Single InAs/GaAs Quantum Dots

Abstract

Results of experimental study of multiexcitonic emission related to the p-shell of single self-assembled InAs/ GaAs quantum dots are presented. Optical properties of a rst emission line to appear from the p-shell of a strongly excited quantum dots are investigated using low-temperature polarization-sensitive micro-photoluminescence measurements. The emission line is attributed to the recombination of a complex of three electrons and holes conned in a dot (neutral triexciton), 3X. It is found that the emission consists of two linearly polarized components and the ne structure splitting is larger than the respective splitting of a neutral exciton. The optical anisotropy of the 3X emission is related to the anisotropy of the quantum dot localizing potential. The axis of the 3X optical anisotropy changes from dot to dot covering broad range within ±50 degrees with respect to the axis dened by the optical anisotropy of a neutral exciton (X). Possible origin of the deviation is discussed.

Influence of the quantum dot geometry on p -shell transitions in differently charged quantum dots

“…Most studies focus on the QD ground states in the prospect of several possible applications within the fields of quantum computing [1], advanced photon sources [2][3][4] and spintronics [5]. Less is known about the higher excited level structure, which is vital for the understanding of time-resolved phenomena like relaxation and dephasing mechanisms [6][7][8], recombinations of multiexcitons with more than two electrons or holes [9][10][11][12][13][14][15][16][17] or resonant absorption characteristics, typically measured via photoluminescence excitation (PLE) spectroscopy [6,[18][19][20].…”

Quadexciton cascade and fine-structure splitting of the triexciton in a single quantum dot

“…The asymmetry of the confining potential affects the two degenerate bright states of the triexciton and splits them into two linearly polarized components, as it was predicted on a theoretical ground 33 and experimentally demonstrated. 34 In the case of quadexciton, there are two configurations regarding the spin of electrons and the angular momentum of holes occupying the p-shell levels: the spin-singlet states (two electrons and two holes are anti-parallel) and the spintriplet states (two electrons and two holes are parallel). 29 In the former case, the anisotropy of the confining potential increases the number of bright excitonic states from two to five, while in the latter one the basic set consists of one configuration only, in which there are two spin-parallel electrons and two angular-momentumparallel holes distributed on two p-shell levels and there is no qualitative difference between the isotropic and anisotropic confinement.…”

“…The asymmetry of the confining potential affects the two degenerate bright states of the triexciton and splits them into two linearly polarized components, as it was predicted on a theoretical ground 33 and experimentally demonstrated. 34 In the case of quadexciton, there are two configurations regarding the spin of electrons and the angular momentum of holes occupying the p-shell levels: the spin-singlet states (two electrons and two holes are anti-parallel) and the spintriplet states (two electrons and two holes are parallel).…”

“…However, for the s-shell emission, the FSS of the triexciton state cannot be studied, because both the initial and final state of the process are split [15]. In contrast, in the p-shell case, only the initial triexciton state has the fine structure (the biexciton state is not split) [17]. In our opinion, the properties of polarized photons emitted within such high-order cascades may bring new information on optical processes and sources of anisotropy in semiconductor QDs.…”

Selection rules for the excitation of quantum dots by spatially structured light beams: Application to the reconstruction of higher excited exciton wave functions

“…In addition to the energetically lowest four levels, i.e., the ground state bright and dark excitons, which play a central role for many applications, also higher excited states become interesting. The latter can be used, e.g., to describe metastable states in charged QDs [31], to create and describe multiexciton states [32][33][34][35][36][37][38][39][40], for state preparation schemes [41,42], to study dephasing and relaxation processes [31,43,44], or for resonant absorption within a QD [43,[45][46][47][48]. To utilize higher excited electronic states, they need to be addressable, selectively excitable, and identifiable.…”