Ordered GaAs quantum dot arrays on GaAs(001): Single photon emission and fine structure splitting

Kiravittaya, Suwit; Benyoucef, M.; Zapf-Gottwick, Renate; Rastelli, Armando; Schmidt, Oliver G.

doi:10.1063/1.2399354

Cited by 76 publications

(65 citation statements)

References 18 publications

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“…In particular, the buffer layer thickness is usually restricted to tens of atomic monolayers (ML) [4,5,[7][8][9][10], depending on the initial size of the pattern features and on the kinetics of the growth mode employed. With respect to the substrate temperature, considering that atom surface migration for III-V compound semiconductors is significant for T S ≥ 500 ºC [4], it would be desirable to maintain the maximum T S as close as possible to 500 ºC, at least in the case of shallow pattern features (a few nanometers).…”

Section: Introductionmentioning

confidence: 99%

“…In order to obtain an actual advantage of their properties, it is mandatory to develop technological processes that allow fabricating QD with accurate control in their size, shape and spatial position. For that purpose, the use of pre-patterned substrates is a quite wide-spread strategy in order to obtain highly ordered arrays of QD using different lithographic approaches [4][5][6][7][8][9][10][11]. In this direction, the preparation of a patterned surface for a subsequent epitaxial growth that allows obtaining selective QD nucleation while keeping their optical emission efficiency just in one single layer of QD is a key factor for a successful application of this approach in devices where stacked layers of QD must be avoided.…”

Section: Introductionmentioning

confidence: 99%

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Improvement of InAs quantum dots optical properties in close proximity to GaAs(001) substrate surface

Martín‐Sánchez¹,

González²,

Alonso‐González³

et al. 2008

Journal of Crystal Growth

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In this work we demonstrate a growth process for obtaining high optical emission efficiency InAs/GaAs(001) quantum dots (QD) formed at short distance to the interface with the GaAs substrate. In particular, after an initial exposure of the substrate surface to long times of atomic hydrogen flux (t H up to 45 min) followed by a posterior growth of a GaAs buffer layer by atomic layer molecular beam epitaxy, both steps at low substrate temperature (T S =450 ºC), an enhancement of InAs QD optical emission efficiency is obtained, even at close proximity (3.5 nm) to the substrate interface. This process fulfils the strict requirements in terms of substrate temperature and buffer layer thickness (distance from the QD to the substrate interface) for its possible use as an optimal regrowth protocol on previously patterned GaAs substrates.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improvement of InAs quantum dots optical properties in close proximity to GaAs(001) substrate surface

Martín‐Sánchez¹,

González²,

Alonso‐González³

et al. 2008

Journal of Crystal Growth

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“…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.…”

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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“…One-dimensionally ordered QDSLs with closely spaced QDs in the z direction is believed to allow QD electron wave functions to overlap and form the desired IB or IBs. There have been several experimental reports of vertical one-dimensional structures 11,12) , as well as three-dimensional ones 13,14,15) , followed by the recent successful fabrication of a QD-IBSC module 16,17) . Further progress in self-assembly growth is expected to result in well-ordered QDSLs with closely spaced QDs to form better IBs.…”

Section: Introductionmentioning

confidence: 99%

Intermediate band electron wave function localization effect on the efficiency limits of InAs/GaAs quantum dot solar cell

Mehdipour¹,

Ogawa²,

Souma³

2014

gseku.e

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In the conventional detailed balance theory of quantum dot intermediate band solar cell (QD-IBSC), the electron wave function is assumed to be completely delocalized. Such wavefunctions are known to reduce thermal losses and enhance the photon-harvesting efficiency of an intermediate band. The aim of this study is to investigate the accuracy of the assumption of such "metallic-like IB" in determining the efficiency of IBSC in the presence of one or two IBs. According to our calculations for cubic model QD structures based on the finite element method, the electronic wave functions are strongly concentrated in the QD regions for the realistic QD spacing. The influence of such electron localization effects on the cell efficiency is then carefully examined by introducing the effective electron filling factor along with the detailed balance theory, with particular attention given to the roles played by the number of IBs and sunlight concentration. While the electron localization in IBs is detrimental for cell efficiency, the use of IBs is demonstrated to be still beneficial and improve the efficiency significantly under full sunlight concentration.

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Ordered GaAs quantum dot arrays on GaAs(001): Single photon emission and fine structure splitting

Cited by 76 publications

References 18 publications

Improvement of InAs quantum dots optical properties in close proximity to GaAs(001) substrate surface

Improvement of InAs quantum dots optical properties in close proximity to GaAs(001) substrate surface

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

Intermediate band electron wave function localization effect on the efficiency limits of InAs/GaAs quantum dot solar cell

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