Confinement regime in self-assembled InAs/InAlGaAs/InP quantum dashes determined from exciton and biexciton recombination kinetics

Abstract

The exciton and biexciton confinement regimes in strongly anisotropic epitaxial InAs nanostructures called quantum dashes (QDashes) embedded in an In0.53Ga0.23Al0.24As matrix, which is lattice-matched to InP(001) substrate, have been investigated. For that purpose, we have performed low-temperature spatially and polarization-resolved photoluminescence and time-resolved photoluminescence measurements on a set of single QDashes. The main conclusions are drawn based on the experimentally obtained distribution of the ratio between the exciton and biexciton lifetimes. We have found that a majority of QDashes for which the abovementioned ratio falls into the range of 1.2 ± 0.1–1.6 ± 0.1 corresponds to the so called intermediate confinement regime, whereas for several cases, it is close to 1 or 2, suggesting reaching the conditions of weak and strong confinement, respectively. Eventually, we support this data with dependence of the lifetimes' ratio on the biexciton binding energy, implying importance of Coulomb correlations, which change significantly with the confinement regime.

Telecom wavelength single quantum dots with very small excitonic fine-structure splitting

“…This suggests that the structure, composition, and other QD parameters are nearly identical in this spectral range 23 . Biexciton binding energies in these QDs are lower than for earlier reported quantum dashes 24,25 or InAs/InP QDs grown by droplet epitaxy 13 and close to the Stranski-Krastanov InAs/InP QDs 26 . We suppose that the small measured excitonic fine-structure splitting values is a direct consequence of both intrinsic InAs/InP material properties and the ripening technique, which allows the formation of highly symmetric QDs.…”

Optical and electronic properties of low-density InAs/InP quantum-dot-like structures designed for single-photon emitters at telecom wavelengths

“…Recent studies have provided explanation of some of their properties, such as partially polarized emission [14], exciton recombination characterized by two distinct lifetimes in the case of asymmetric dots [15] or the structure of excited states [16]. They have also raised a question regarding the exciton confinement regime [17,18]. These results were, however, obtained mostly for very dense ensembles of elongated QDs [19], and thus characterization of carrier confinement and the resulting optical properties of low-density QDs, growing in a different geometry such as those considered here, is needed.…”

From quantum dots to quantum dashes: Excitonic spectra of highly elongated InAs/InP nanostructures

“…[9][10][11] The realm of InAs/InP nanostructures is rich and varies from more conventional cylindrical self-assembled, 12,13 and nanowire quantum dots [14][15][16] to rather unconventional semiconductor nanostructures with characteristic large in-plane elongation, known as quantum dashes. [17][18][19][20][21][22][23][24][25][26][27] Quantum dashes have demonstrated their potential for utilization in e.g. lasers and amplifiers 19,20,28 or single photon emitters.…”