Increase of charge-carrier redistribution efficiency in a laterally organized superlattice of coupled quantum dots

Abstract

We report the observation of enhanced charge-carrier redistribution in laterally organized and coupled InAs/ InP quantum dots ͑QDs͒. We show that a periodic organization appears in the QD plane for a high in-plane QD density ͑QDD͒. This organization enhances the lateral coupling between the dots, which is evidenced by photoluminescence and magnetophotoluminescence experiments. Electronic inter-QD lateral coupling results in an improved charge-carrier distribution at low temperature, as shown by electroluminescence on high QDD QD lasers. We conclude that the inter-QD tunneling occurs via the tunneling of excited states through the wetting layer, and discuss the prospects of using coupled QDs for improving the quantum efficiency and dynamical properties of QD lasers.

Heterodimensional charge-carrier confinement in stacked submonolayer InAs in GaAs

“…Coupling of excited electron QD states has already been used in the InAs/InP system to improve laser performance, but this involved a somewhat more complex stacking procedure to encourage the formation of a lateral superlattice [34], and would have an insignificant effect on the hole distribution. Similarly, it has also been demonstrated that the inclusion of an InGaAs QW injector layer close to InAs QDs allows rapid tunneling of electrons into the lasing QD states, improving the modulation bandwidth of near-infrared QD lasers from ∼7 to ∼22 GHz [3].…”

Semianalytical model for simulation of electronic properties of narrow-gap strained semiconductor quantum nanostructures

“…Our previous results on InAs/InP QD were obtained either using a complete 3D 8-band k.p strained Hamiltonian [9] or a simple 1-band k.p Hamiltonian with strain renormalized constants in 2D cylindrical coordinates [13]. We may notice that InAs QD grown either on (100) or (311)B misoriented surface are interesting for applications purposes [14,15]. The present model is however expected to be applied only to QD grown on (100) with cylindrical symmetry.…”

“…The other components of the strained Hamiltonian can be given in cylindrical coordinates without adding any more approximations : our previous full-3D study [9] and experimental results [13,14]. The variation of hydrostatic the confining potentials (hydrostatic strain) for HH and CB are almost constant inside the conic QD, whereas LH potential is stabilized at the top of the cone thanks to the inverted biaxial strain [9].…”

Effect of the nitrogen incorporation and fast carrier dynamics in (In,Ga)AsN/GaP self-assembled quantum dots

“…Therefore no evidence of carrier redistribution can be seen between the two involved states, confirming the independence of the optical transitions, even at room temperature. 19 A first activation energy is found to be a few meV, and a second one a few tens of meV. This reflects a similarity between the quantum states involved in the recombination process, which tends to favor the hypothesis of a QD bimodal distribution.…”