Competitive carrier interactions influencing the emission dynamics of GaAsSb-capped InAs quantum dots

Abstract

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Excitonic structure and pumping power dependent emission blue-shift of type-II quantum dots

“…We comment here on the origin of the blue-shift of the emission energy ∆E with increasing P in type II which we observe in our PL measurements. Currently, two competing hypotheses are put forward in this respect: the "state-filling" model, stemming from the observation of the large radiative lifetime of the emission from type-II QDs 15,28,[45][46][47] which occurs due to the smaller overlap between electron and hole wavefunctions 12,14 . If the pumping rate exceeds the emission rate of the ground state transition, which is often the case in type-II QDs, a larger proportion of the radiative transitions between electronic levels higher in energy than the ground state results.…”

Type II InAs/GaAsSb quantum dots: Highly tunable exciton geometry and topology

“…Depending on the amount of Sb, this redshift comes along with a transition from type I to type II band alignment at the QD interfaces. [19][20][21][22] For the particular amount of Sb used in the cap layer in the present work, the valence band alignment across the GaAsSb/InAs interfaces turns from type I to type II, leaving the electrons confined within the InAs QD, while expelling the holes to the capping layer already at zero electric field. Besides the type II band alignment, the vicinity of the top GaAsSb/GaAs interface, located a few nanometers above the QD apex, is a key element in our design (see inset in Figure 1(b)).…”

Optical Emission of a Strained Direct-Band-Gap Ge Quantum Well Embedded Inside InGaAs Alloy Layers

“…The optical characterization was performed at 10 K via microphotoluminescence (-PL) and micro-time-resolved PL (-TRPL), as described in Ref. [26]. In both cases the laser was focused using a high numerical aperture objective on a spot of $5 m diameter on the sample surface.…”