Formation of lateral quantum dot molecules around self-assembled nanoholes

Songmuang, R.; Kiravittaya, Suwit; Schmidt, Oliver G.

doi:10.1063/1.1569992

Cited by 169 publications

(140 citation statements)

References 12 publications

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“…This fact is especially interesting for applications based on a single QD. Furthermore, in coincidence with other lithographic techniques, 12 a different number of QD per nanohole can also be obtained. 13 In this situation, one advantage of the droplet epitaxy technique is that it can provide nanotemplates for QD formation without the need of growing thick buffer layers to avoid the influence of residual contamination from the fabrication process on the optical properties of the nanostructures.…”

mentioning

confidence: 99%

Formation and optical characterization of single InAs quantum dots grown on GaAs nanoholes

Alonso‐González¹,

Alén²,

Fuster³

et al. 2007

Applied Physics Letters

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We present a study of the structural and optical properties of InAs quantum dots formed in a low density template of nanoholes fabricated by droplet epitaxy on GaAs ͑001͒. The growth conditions used here promote the formation of isolated quantum dots only inside the templated nanoholes. Due to the good optical quality and low density of these nanostructures, their ensemble and individual emission properties could be investigated and related to the particular growth method employed and the quantum dot morphology. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2799736͔ New nanoelectronics and quantum information perspectives require the ability of growing nanostructures with control in size and spatial location. In particular, for the application of quantum devices based in single quantum dots 1,2 ͑QDs͒ as, for instance, single photon emitters, it is necessary to combine strategies that would permit precise location of a single nanostructure presenting at the same time high optical quality. [3][4][5][6] With this aim, a quite wide-spread strategy to overcome the randomly positioning of self-assembled nanostructures is based on the use of patterned substrates to create preferential nucleation sites that define the position and size of the nanostructures. In particular, highly ordered arrays of QDs have been already obtained using different lithographic approaches followed by an appropriate regrowth process. 5,7,8 In this situation, the droplet epitaxy has revealed itself as a potential technique to achieve templates for localization of nanostructures with high optical quality in latticemismatched heteroepitaxial systems. 9 This technique has been mainly developed in GaAs based systems and basically consists of the supply of a certain amount of Ga during growth to form metallic droplets on the surface, which are later transformed into crystalline GaAs under arsenic atmosphere. Under certain experimental conditions, the crystallization process leads to the formation of specific structures containing nanoholes that act as preferential sites for InAs QD nucleation upon further InAs deposition. 10 The density of nanoholes corresponds to that of the droplets, being possible to obtain QD densities as low as 10 7 cm −2 . 11 The size of these nanostructures is related to the amount of InAs filling the nanoholes, with independence of their density, as opposed to the QD formation by self-assembling processes. This fact is especially interesting for applications based on a single QD. Furthermore, in coincidence with other lithographic techniques, 12 a different number of QD per nanohole can also be obtained. 13 In this situation, one advantage of the droplet epitaxy technique is that it can provide nanotemplates for QD formation without the need of growing thick buffer layers to avoid the influence of residual contamination from the fabrication process on the optical properties of the nanostructures.This work deals with the structural and optical characterization of InAs QDs formed in a template of 2.4 ϫ 10 8 cm −2 nano...

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mentioning

confidence: 99%

Formation and optical characterization of single InAs quantum dots grown on GaAs nanoholes

Alonso‐González¹,

Alén²,

Fuster³

et al. 2007

Applied Physics Letters

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“…Before any InAs deposition, we observe that the surface presents randomly located nanoholes with an elongated structure along [110] direction and a density of 2 × 10 -8 cm -2 . Their dimensions are h ) 4.4 ( 0.7 nm for the nanoholes depth and D 1 ) 43 ( 3 nm and D 2 ) 95 ( 5 nm for the nanoholes mean diameter along [1][2][3][4][5][6][7][8][9][10] and [110] directions, respectively. On this kind of patterned surface, 1.5 ML of InAs are deposited using two different As 2 pressures while keeping the rest of growth parameters constant.…”

Section: Methodsmentioning

confidence: 99%

“…2 In this sense, the ability to obtain a precise control in size, spatial location, and number of nanostructures has become a highly desirable issue. [4][5][6] In particular, the formation of different distributions of QD in close proximity 7 permits a precise study of coupling and coherence that is strictly necessary for the creation of future functional units in the field of quantum computing and communication. 8 In this way, the growth of vertically stacked self-assembled QD has been deeply studied during the last years allowing the direct observation of controlled coupling in a quantum dot molecule (QDM).…”

Section: Introductionmentioning

confidence: 99%

Formation of Lateral Low Density In(Ga)As Quantum Dot Pairs in GaAs Nanoholes

Alonso‐González¹,

Martín‐Sánchez²,

González³

et al. 2009

Crystal Growth & Design

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ABSTRACT:In this work we present a growth procedure to form lateral In(Ga)As quantum dot pairs by using a low density, 2 × 10 8 cm -2 , GaAs nanohole template previously formed in situ by droplet homoepitaxy. In particular, by changing the arsenic pressure at which InAs is grown on the template, we demonstrate the possibility to select the formation of single quantum dots (QD) or QD pairs inside each of the nanoholes. In the case of QD pairs, the ensemble photoluminescence (PL) as a function of excitation power and temperature reveals spectral signatures typical of laterally coupled nanostructures.

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“…13 In these systems, the process of island and pit nucleation leads to surface patterning in which features on the surface are correlated to approximately 150 nm. It has been shown that pits may act as nucleation sites for islands, 11,14 resulting in island distributions and densities suitable for application such as cellular automata. 15 These experimental observations form the basis of the theoretical analysis presented here, in which we consider the nucleation of a secondary feature, in this case a pit, on a surface upon which primary features, 3D islands, have already nucleated.…”

Section: Introductionmentioning

confidence: 99%

Pit nucleation in the presence of three-dimensional islands during heteroepitaxial growth

2004

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We present a model in which pit nucleation in thin films is considered to arise from a nearequilibrium nucleation process. In this model the adatom concentration plays a central role in controlling the morphological development of the surface. Although pits relieve elastic energy more efficiently than islands, pit nucleation can be prevented by a high adatom concentration.Three-dimensional islands act as adatom sinks and the lower adatom density in their vicinity promotes pit nucleation. Thermodynamic considerations predict several different growth regimes in which pits may nucleate at different stages of growth depending on the growth conditions and materials system. However direct comparisons to experimental observations require that kinetics be taken into account as well. The model predicts a wide range of possible morphologies: planar films, islands alone, islands nucleation followed by pit nucleation, and pits alone. The model shows good agreement with experimental observations in III-V systems given the uncertainties in quantifying experimental parameters such as the surface energy.

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Formation of lateral quantum dot molecules around self-assembled nanoholes

Cited by 169 publications

References 12 publications

Formation and optical characterization of single InAs quantum dots grown on GaAs nanoholes

Formation and optical characterization of single InAs quantum dots grown on GaAs nanoholes

Formation of Lateral Low Density In(Ga)As Quantum Dot Pairs in GaAs Nanoholes

Pit nucleation in the presence of three-dimensional islands during heteroepitaxial growth

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