Laser devices with stacked layers of InGaAs/GaAs quantum rings

Suarez, Ferran; Granados, Daniel; Dotor, María Luisa; García, J. M.

doi:10.1088/0957-4484/15/4/003

Cited by 79 publications

(42 citation statements)

References 19 publications

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“…While c is 1.65 ML for the first layer, in the samples with 1.5 and 3 nm GaAs spacers the nucleation of the second and the third layers takes place for a coverage significantly below ͑ϳ1.35 ML͒. 11 This effect is also observed in stacked QDs due to strong In segregation and strain propagation effect. [12][13][14] For spacers of 4.5 nm or thicker, c is 1.65 ML for all QD layers.…”

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confidence: 88%

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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confidence: 88%

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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“…This spacer ensures well-developed a e-mail: ouerghuiwalid@yahoo.fr rings with optical emission like that of single layers. The multimodal stimulated emission is centred on 930 nm at 77 K and it has a minimum threshold current density per QR layer of 69 A cm −2 [8], which is not a bad value. The aim of this work is to understand the exciton recombination dynamics at low and high temperatures in such a kind of QR multilayer structures.…”

Section: Introductionmentioning

confidence: 97%

“…A precise control over the QD height, width and shape is of crucial importance, since the geometry has a clear influence on the quantum confinement of the charge carriers and hence determines QD optical properties. In this sense, some strategies have been recently developed to change the shape and size of InAs QD during the growth of the InAs layer and subsequent capping with a thin barrier material of GaAs [7][8][9]. Following this method, quantum rings (QR) can be obtained, which exhibit interesting basic optical properties [10].…”

Section: Introductionmentioning

confidence: 99%

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Effect of carrier transfer on the PL intensity in self-assembled In (Ga) As/GaAs quantum rings

Ouerghui

Martı́nez-Pastor

Gomis

et al. 2006

Eur. Phys. J. Appl. Phys.

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Abstract. We present results concerning the carrier transfer between In(Ga)As quantum rings in a stacked multilayer structure, which is characterised by a bimodal size distribution. This transfer of carriers explains the observed temperature behaviour of diode lasers based on that kind of stacked layer structures. The inter-ring carrier transfer can be possible by phonon assisted tunnelling from the ground state of the smallring family towards the big-ring family of the bimodal size distribution. This process is thermally activated in the range 40-80 K. PACS

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“…In particular, self-assembled QRs of InGaAs grown on GaAs are potential candidates for the development of laser diodes at 980 nm at room temperature and high-speed optoelectronic devices. Stacked layers of QR have been grown for different GaAs spacers, demonstrating the laser operation in the most favourable cases [4]. The QR system allows a great density of multilayer stacks, because of their reduced height, more than three times smaller than typical QD, while avoiding excessive electronic coupling.…”

Section: Introductionmentioning

confidence: 99%

Exciton Dynamics in Stacked InGaAs/GaAs Quantum Rings Under Resonant Excitation

Naouari¹,

Ouerghui²,

Martı́nez-Pastor³

et al. 2011

JMP

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We report systematic temperature-dependent measurements of photoluminescence spectra in self-assembled InGaAs/GaAs quantum rings (QRs) under resonant excitation condition. We have studied the rise in temperature of the ground-state intensity. The carrier transfer between the ground state of the small ring family towards the big-ring family of the bimodal size distribution is identified by analyzing the photoluminescence spectra. This effect is observed in very thin spacer and under resonant excitation. This situation makes important the lateral tunneling of excitons between rings under low temperatures (10 K). Tunneling time about 1ns was estimated at low temperature and compared to similar carrier transfer in quantum dots (QDs) found in the literature.

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Laser devices with stacked layers of InGaAs/GaAs quantum rings

Cited by 79 publications

References 19 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)

Effect of carrier transfer on the PL intensity in self-assembled In (Ga) As/GaAs quantum rings

Exciton Dynamics in Stacked InGaAs/GaAs Quantum Rings Under Resonant Excitation

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