Tuning of the electronic levels in vertically stacked InAs/GaAs quantum dots using crystal growth kinetics

Gerardot, Brian D.; Shtrichman, I.; Hebert, Damon; Petroff, P. M.

doi:10.1016/s0022-0248(02)02516-2

Cited by 21 publications

(18 citation statements)

References 29 publications

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“…QDs are particularly interesting for their potential use in detectors, memories, quantum computing and photonic devices applications. [1][2][3][4] The development and design of QDs based devices requires a precise control of the morphology and composition of the QDs. As an example of the achieved capabilities to control QDs size and shape it has been proved that it is possible to self-assemble In͑Ga͒As quantum rings ͑QRs͒.…”

mentioning

confidence: 99%

Vertical order in stacked layers of self-assembled In(Ga)As quantum rings on GaAs (001)

Granados¹,

García²,

Ben

et al. 2005

Applied Physics Letters

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Stacked layers of self-assembled In͑Ga͒As quantum rings on GaAs grown by solid source molecular beam epitaxy are studied by ex situ atomic force microscopy ͑AFM͒, low temperature photoluminescence ͑PL͒ and cross-sectional transmission electron microscopy ͑XTEM͒. The influence of the strain field and InAs segregation on the surface morphology, optical properties and vertical ordering of three quantum ring layers is analyzed for GaAs spacers between layers from 1.5 to 14 nm. AFM and PL results show that samples with spacers Ͼ6 nm have surface morphology and optical properties similar to single layers samples. XTEM results on samples with 3 and 6 nm GaAs spacers show that the rings are preserved after capping with GaAs, and evidence the existence of vertically ordered quantum rings. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1866228͔ Molecular beam epitaxy ͑MBE͒ is a powerful technique for the fabrication of lattice mismatched semiconductor nanostructures. In particular, InAs on GaAs ͑001͒ selfassembled quantum dots ͑QDs͒ are one of the most studied systems. QDs are particularly interesting for their potential use in detectors, memories, quantum computing and photonic devices applications. [1][2][3][4] The development and design of QDs based devices requires a precise control of the morphology and composition of the QDs. As an example of the achieved capabilities to control QDs size and shape it has been proved that it is possible to self-assemble In͑Ga͒As quantum rings ͑QRs͒. 5 QRs are obtained by covering a layer of QDs with a thin cap ͑ϳ20% of the dot height͒ followed by a growth pause. In this way, the original islands reshape into ring-like structures. 6 Several authors have reported interesting differences in the optical and confining properties between QDs and QRs. Pettersson et al. 7 found an oscillator strength for the fundamental transition three times higher for QRs than for QDs. Warburton et al. 8 showed that the permanent dipole moment of exciton in QRs is three times higher and with opposite sign than those found for lens shaped QDs. Lorke et al. 9 proved that the ground state of QRs with zero angular momentum transits into a chiral state under the influence of an external magnetic field, concluding that ring shaped morphology translates into a ring-like electronic structure. Their nontrivial geometry, together with the possibility of controlling the energy levels, oscillator strength, polarizability and magnetic properties, make QRs good candidates for the development of new devices. The use of stacked layers increases quantum efficiency and avoids saturation gain effects in laser devices. 10 In the case of QRs, stacking the nanostructures is even more important, as the large in-plane mean dimensions of the rings ͑100 nmϫ 90 nm by AFM͒ require low density ring ensembles ͑1-9 ϫ 10 9 cm −2 ͒ to avoid overlap problems.In spite of all the work focused on optical characterization, little is known about the structural properties of embedded rings. This work mainly presents structural charact...

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mentioning

confidence: 99%

Vertical order in stacked layers of self-assembled In(Ga)As quantum rings on GaAs (001)

Granados¹,

García²,

Ben

et al. 2005

Applied Physics Letters

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“…The two QDs are referred in the following as top (T ) and bottom (B), and they are separated by a distance R. This distance can be precisely controlled by tuning the growth conditions of the dots [24], which is fixed to R = 8.4 nm in the following. Additionally, an external electric field, denoted F in the following, can be applied to the dimer of QDs when the latter is placed in an n-i Schottky barrier [26,27].…”

Section: Biexciton Generation In Coupled Quantum Dotsmentioning

confidence: 99%

“…[49], we fix the excitation energy of the top QD to E10 10 X = 1.587 eV. The energy of the bottom QD can be precisely controlled experimentally by tuning its chemical or structural parameters [24,25,49]. As reported in Ref.…”

Section: A Energy Levels and Mutual Couplings In Cqdsmentioning

confidence: 99%

“…As reported in Ref. [24], we consider a detuning of 10 meV between the two QDs and fix E01 01 X = 1.597 eV.…”

Section: A Energy Levels and Mutual Couplings In Cqdsmentioning

confidence: 99%

“…The energy levels and mutual electronic and excitonic couplings between the dots can be finely tuned by engineering their structure and by carefully controlling the interdot distance [22][23][24][25]. The possibility to apply an electric field along the dimer [26,27] using an external gate voltage adds a supplementary means to control these energy levels [28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

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Cooperative biexciton generation and destructive interference in coupled quantum dots using adiabatic rapid passage

Renaud

Grozema

2014

Phys. Rev. B

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We report numerical simulations of biexciton generation in coupled quantum dots (CQDs) placed in a static electric field and excited by a chirped laser pulse. Our simulations explicitly account for exciton-phonon interactions at finite temperature using a non-Markovian quantum jump approach to solve the excitonic dynamics. In the case of noninteracting quantum dots, the biexciton generation is severely limited by the biexciton binding energy. We demonstrate that the application of an axial electric field along the CQDs can yield a favorable excitonic level alignment that compensates for the biexciton binding energy and yields an optimum biexciton generation. On the contrary, well-defined values of the electric field lead to destructive quantum interference that completely inhibits the biexciton generation. We therefore demonstrate here the potential of chirped pulse excitations of CQDs for high-efficiency biexciton generation but also for the control of unique optoelectronic properties of complex quantum systems.

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2009

Spins in Optically Active Quantum Dots

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Tuning of the electronic levels in vertically stacked InAs/GaAs quantum dots using crystal growth kinetics

Cited by 21 publications

References 29 publications

Vertical order in stacked layers of self-assembled In(Ga)As quantum rings on GaAs (001)

Vertical order in stacked layers of self-assembled In(Ga)As quantum rings on GaAs (001)

Cooperative biexciton generation and destructive interference in coupled quantum dots using adiabatic rapid passage

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