Room-temperature 1.6μm light emission from InAs∕GaAs quantum dots with a thin GaAsSb cap layer

Liu, H. Y.; Steer, M. J.; Badcock, T. J.; Mowbray, D. J.; Skolnick, M. S.; Suarez, Ferran; Ng, Jo Shien; Hopkinson, M.; David, J.P.R.

doi:10.1063/1.2173188

Cited by 90 publications

(70 citation statements)

References 23 publications

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“…The calculated hole wavefunctions consist again of two segments. Now, however, the segments are oriented along [1][2][3][4][5][6][7][8][9][10] crystal direction and the whole wavefunction resides above the QD. The energies of the four lowest states of two holes in this structure, calculated by CI with 10 basis single particle states, formed a singlet and a triplet separated by the energy of 325 µeV.…”

Section: Resultsmentioning

confidence: 99%

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Type-II InAs/GaAsSb/GaAs Quantum Dots as Artificial Quantum Dot Molecules

2016

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We have studied theoretically the type-II GaAsSb capped InAs quantum dots for two structures differing in the composition of the capping layer, being either (i) constant or (ii) with Sb accumulation above the apex of the dot. We have found that the hole states are segmented and resemble the states in the quantum dot molecules. The two-hole states form singlet and triplet with the splitting energy of 4 µeV / 325 µeV for the case (i) / (ii). We have also tested the possibility to tune the splitting by vertically applied magnetic field. As the predicted tunability range was limited, we propose an approach for its enhancement.

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Section: Resultsmentioning

confidence: 99%

“…InAs quantum dots (QDs) on GaAs substrate covered by the GaAs 1−y Sb y capping layer (CL) exhibit a lot of interesting properties [1,2]. The prominent one is the possibility to tune the type of the band alignment continuously from type-I to type-II by changing the Sb content in the layer [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Type-II InAs/GaAsSb/GaAs Quantum Dots as Artificial Quantum Dot Molecules

2016

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“…The strong red shift observed by using GaAsSb instead of GaAs capping layers has been attributed to a type II band alignment [64,70]. However, the structural properties of these QDs have not been studied, despite the fact that they could be significantly different from those of GaAs-capped QDs.…”

Section: Gaassb Capping Of Inas/gaas Qdsmentioning

confidence: 99%

“…In the last few years, GaAsSb capping layers have also been used to increase the emission wavelength of InAs/GaAs QDs [63,69] and room temperature photoluminescence at 1.6\xm has recently been reported from GaAsSb-capped In(Ga)As/GaAs QDs [64,70]. The strong red shift observed by using GaAsSb instead of GaAs capping layers has been attributed to a type II band alignment [64,70].…”

Section: Gaassb Capping Of Inas/gaas Qdsmentioning

confidence: 99%

InAs Quantum Dot Formation Studied at the Atomic Scale by Cross-sectional Scanning Tunnelling Microscopy

Ulloa

Offermans

Koenraad

2008

Handbook of Self Assembled Semiconductor Nanostructures for Novel Devices in Photonics and Electronics

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Introduction Quantum dot formationSelf-assembled quantum dots (QDs) have attracted much attention in the last years [1,2]. These nanostructures are very interesting from a scientific point of view because they form nearly ideal zero-dimensional systems in which quantum confinement effects become very important. These unique properties also make them very interesting from a technological point of view. For example, InAs QDs are employed in QD lasers [3,4], single electron transistors [5], midinfrared detectors [6,7], single-photon sources [8,9], etc. InAs QDs are commonly created by the Stranski-Krastanov growth mode when InAs is deposited on a substrate with a bigger lattice constant, like GaAs or InP [10]. Above a certain critical thickness of InAs, three-dimensional islands are spontaneously formed on top of a wetting layer (WL) to reduce the strain energy. Once created, the QDs are subsequently capped, a step which is required for any device application.For any application based on InAs QDs, an accurate control of their electronic properties is required. The electron and hole states in the dot are very sensitive to the QD size, shape and composition (as well as to the surrounding material), and therefore an accurate control of the QD structural properties is necessary for applications. This explains the strong effort dedicated in the last years to the structural characterization of QDs [11], which is essential in order to have a deep understanding of the QD formation process. Although a lot of effort has been dedicated to study surface QDs, there are relatively few studies focused on the effect of the capping process [12][13][14][15][16][17][18][19][20]. Some of these studies have already shown significant differences in size, shape and composition between uncapped and capped QDs. For example, an important collapse of the QD height has been reported for InAs/GaAs QDs capped with GaAs [14,15,[17][18][19], revealing the big influence of the capping process on the structural properties of the QDs. Indeed, critical issues affecting the dot take place during capping like dot decomposition, intermixing, segregation, As/P exchange and composition modulation in the capping layer. This means that the real buried QDs must be studied in order to understand the complete QD formation process. Cross-sectional scanning tunnelling microscopy is an especially useful technique for this purpose, because it allows the structure of the capped dots at the atomic scale to be assessed. Cross-sectional scanning tunnelling microscopy (X-STM)The scanning tunnelling microscope is part of the family of scanning probe microscopes, which are able to provide direct real space information of a physical property at the atomic scale. This

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“…Particularly, its type-II band alignment provides an excellent opportunity to improve the performance of both heterojunction bipolar transistors and optoelectronic devices due to their nature of the separation of photo-excited electrons and holes [1][2][3][4]. Therefore, InAs/GaAsSb/GaAs system is very attractive for both of academic interest and industrial application.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Localized Electric Field in the Type-II InAs/GaAsSb/GaAs Structure

et al. 2016

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The effect of localized electric field (F ) was investigated in the type-II InAs/GaAsSb/GaAs structures. To compare type-I to type-II, two types of samples with different Sb contents was grown by molecular beam epitaxy, whose Sb contents are 3% (type-I) and 16% (type-II), respectively. In the both samples, we performed excitation power dependent-photoreflectance at 10 K and the result showed that the period of the Franz-Keldysh oscillation, revealed above the band gap (Eg) of GaAs, was broadened in the only type-II system, which means that F was also increased because it is proportional to the period of the Franz-Keldysh oscillation while the period of the Franz-Keldysh oscillations stayed unchanged in type-I system. This phenomenon is explained by that the F was affected by the band bending effect caused by the spatially separated photo-excited carriers in the interface between GaAsSb and GaAs. The F changed linearly as a function of square root of excitation power as expected for the F . Moreover, F was calculated using fast Fourier transform method for a qualitative analysis, which is in a good agreement with the theory of triangular well approximation.

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Room-temperature 1.6μm light emission from InAs∕GaAs quantum dots with a thin GaAsSb cap layer

Cited by 90 publications

References 23 publications

Type-II InAs/GaAsSb/GaAs Quantum Dots as Artificial Quantum Dot Molecules

Type-II InAs/GaAsSb/GaAs Quantum Dots as Artificial Quantum Dot Molecules

InAs Quantum Dot Formation Studied at the Atomic Scale by Cross-sectional Scanning Tunnelling Microscopy

Investigation of Localized Electric Field in the Type-II InAs/GaAsSb/GaAs Structure

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