Hybrid type-I InAs/GaAs and type-II GaSb/GaAs quantum dot structure with enhanced photoluminescence

Ji, Hao; Liang, Baolai; Simmonds, Paul J.; Juang, Bor‐Chau; Yang, Tao; Young, Robert J.; Huffaker, Diana L.

doi:10.1063/1.4914895

Cited by 18 publications

(4 citation statements)

References 21 publications

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“…Under these conditions, the In atoms have a long migration length and thereafter preferentially incorporate into existing QDs rather than forming new SQDs. This has been observed previously in the AFM of similarly grown QD samples [21][22][23][24]. For these low-density InAs QDs, the average distance between neighbouring QDs is estimated to be ∼125 nm, almost double of the average QD diameter.…”

Section: Resultssupporting

confidence: 83%

PL of low‐density InAs/GaAs quantum dots with different bimodal populations

Wang

Sheng

Liu

et al. 2017

Micro & Nano Letters

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Optical response of the indium arsenide (InAs)/gallium arsenide (GaAs) quantum dots (QDs) with a bimodal distribution is investigated through varying an initial GaAs capping layer between 35 and 18 monolayers. Photoluminescence (PL) measurements confirm that a thinner initial capping layer can reduce the QD dimensions and also modify the population ratio between the large QDs and the small QDs. Therefore, PL quenching related to QD dimension and carrier transfer between the bimodal QD populations has been affected. Manipulation of the initial GaAs capping layer provides a feasible approach to tailor the formation and optical performance of InAs QDs for optoelectronic device applications.

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Section: Resultssupporting

confidence: 83%

PL of low‐density InAs/GaAs quantum dots with different bimodal populations

Wang

Sheng

Liu

et al. 2017

Micro & Nano Letters

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“…Since the confinement for holes in the CL is larger for type I than for type II, the emission energy of GaAs-CL band is larger in type I. The energy of the GaAs-CL band also blue-shifts with pumping by a much larger amount than for the q-type-I QD bands and, thus, this structure represents a coexistence of type-I and type-II confinement45.…”

Section: Methodsmentioning

confidence: 95%

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

Klenovský

Steindl

Geffroy

2017

Sci Rep

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In this work we study theoretically and experimentally the multi-particle structure of the so-called type-II quantum dots with spatially separated electrons and holes. Our calculations based on customarily developed full configuration interaction ap- proach reveal that exciton complexes containing holes interacting with two or more electrons exhibit fairly large antibinding energies. This effect is found to be the hallmark of the type-II confinement. In addition, an approximate self-consistent solution of the multi-exciton problem allows us to explain two pronounced phenomena: the blue-shift of the emission with pumping and the large inhomogeneous spectral broadening, both of those eluding explanation so far. The results are confirmed by detailed intensity and polarization resolved photoluminescence measurements on a number of type-II samples.

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“…However, the induced spatial separation between electron and hole wavefunctions has been demonstrated to lead to considerable quenching of photoluminescence (PL) emission in quantum rings grown by droplet epitaxy [24]. In conventional MBE growth, the coupling between different nanostructures like quantum wells (QWs) and conventional quantum dots (QDs) has been employed in order to recover part of the quenched PL emission [25,26]. Following this idea, recent developments in solar cell applications in the visible and infrared ranges have relied heavily on the enhancement of light absorption in QW/QD coupled systems [27,28] and of carrier lifetimes due to type-II alignment [29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Band structure engineering in strain-free GaAs mesoscopic systems

et al. 2020

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We investigate the optical properties of strain-free mesoscopic GaAs/AlxGa1 − xAs structures (MGS) coupled to thin GaAs/AlxGa1 − xAs quantum wells (QWs) with varying Al content (x). We demonstrate that quenching the QW emission by controlling the band crossover between AlGaAs (X-point) and GaAs (Γ-point) gives rise to long carrier lifetimes and enhanced optical emission from the MGS. For x = 0.33, QW and MGS show typical type-I band alignment with strong QW photoluminescence emission and much weaker sharp recombination lines from the MGS localized exciton states. For x ≥ 0.50, the QW emission is considerably quenched due to the change from type-I to type-II structure while the MGS emission is enhanced due to carrier injection from the QW. For x ≥ 0.70, we observe PL quenching from the MGS higher energy states also due to the crossover of X and Γ bands, demonstrating spectral filtering of the MGS emission. Time-resolved measurements reveal two recombination processes in the MGS emission dynamics. The fast component depends mainly on the X − Γ mixing of the MGS states and can be increased from 0.3 to 2.5 ns by changing the Al content. The slower component, however, depends on the X − Γ mixing of the QW states and is associated to the carrier injection rate from the QW reservoir into the MGS structure. In this way, the independent tuning of X − Γ mixing in QW and MGS states allows us to manipulate recombination rates in the MGS as well as to make carrier injection and light extraction more efficient.

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Hybrid type-I InAs/GaAs and type-II GaSb/GaAs quantum dot structure with enhanced photoluminescence

Cited by 18 publications

References 21 publications

PL of low‐density InAs/GaAs quantum dots with different bimodal populations

PL of low‐density InAs/GaAs quantum dots with different bimodal populations

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

Band structure engineering in strain-free GaAs mesoscopic systems

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