Composition of InAs quantum dots on GaAs(001): Direct evidence for (In,Ga)As alloying

Joyce, P. B.; Krzyzewski, T. J.; Bell, Gavin R.; Joyce, B. A.; Jones, T. S.

doi:10.1103/physrevb.58.r15981

Cited by 307 publications

(174 citation statements)

References 22 publications

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“…Thus, the island formation requires considerable mass transfer by surface diffusion from the WL to the islands, as evidenced by several experiments. [12][13][14][15][16][17][18] The aim of the present study is to elucidate the underlying microscopic processes. As a first step in this direction, some of us have previously investigated the effect of strain on In diffusion on the GaAs͑001͒-c(4ϫ4) surface.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic diffusion of In adatoms on pseudomorphicInxGa1−xAsfilms: First-p

et al. 2004

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In the Stranski-Krastanow growth of strained pseudomorphic films, material transport by surface diffusion plays a crucial role for the development of the three-dimensional island morphology. In an attempt to elucidate the atomistic aspects of this growth mode, we study diffusion of a single indium adatom on (1ϫ3)-and (2 ϫ3)-reconstructed subcritical In 2/3 Ga 1/3 As(001) films using first-principles total energy calculations of the corresponding adiabatic potential-energy surfaces ͑PES͒. We find that In diffusion is anisotropic, and substantially enhanced compared to the conventional GaAs͑001͒-c(4ϫ4) substrate. Special attention is also paid to the methodology of deriving the tracer diffusion coefficients of indium from knowledge of the PES, using the continuous-time random-walk formalism.

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Section: Introductionmentioning

confidence: 99%

Anisotropic diffusion of In adatoms on pseudomorphicInxGa1−xAsfilms: First-p

et al. 2004

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“…For the deposition of In x Ga 12x As on GaAs, several theoretical and experimental studies have shown that, due to segregation effects, the islands' InAs content is significantly enhanced at the expense of InAs in the surrounding two-dimensional film, the so-called wetting layer [6][7][8]. On the other hand, if pure InAs is deposited as epilayer material, the resulting islands may consist of InGaAs: Joyce et al have found evidence for alloying in uncapped InAs islands on GaAs for growth temperatures above 420 ± C, and thus have suggested that significant Ga mass transport occurs [9]. Indeed recent investigations of the electronic properties indicate substantial composition gradients [10].…”

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confidence: 99%

“…Several recent experiments [7,9,22,23] suggest that the conventional picture of Stranski-Krastanow growth may be too simple, and strong dependencies of the growth mode on growth parameters such as temperature, flux rates, and flux ratios [24][25][26] have been reported. With our method we can quantitatively determine the composition and strain profiles of free-standing quantum dots.…”

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confidence: 99%

Nanometer-Scale Resolution of Strain and Interdiffusion in Self-AssembledInAs/GaAsQuantum Dots

et al. 2000

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Tomographic nanometer-scale images of self-assembled InAs͞GaAs quantum dots have been obtained from surface-sensitive x-ray diffraction. Based on the three-dimensional intensity mapping of selected regions in reciprocal space, the method yields the shape of the dots along with the lattice parameter distribution and the vertical interdiffusion profile on a subnanometer scale. The material composition is found to vary continuously from GaAs at the base of the dot to InAs at the top.

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“…However, in the case of InAs/GaAs, recent investigations suggest that, for higher temperature growths, there is significant mass transport from both the wetting layer and the substrate to the islands. 16 Furthermore, the wetting layer in InAs/GaAs systems has been reported to be an ͑In,Ga͒As alloy with temperature dependent composition. 17 The composition of the alloy wetting layer will certainly affect any subsequent island growth procedure.…”

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confidence: 99%

Strain relaxation by alloying effects in Ge islands grown on Si(001)

et al. 1999

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Transmission electron microscopy is used to study the morphology and the composition profile of ''pure'' Ge islands grown at high temperature on Si͑001͒ by molecular beam epitaxy. An alloying process, involving mass transport from the substrate to the islands during the island growth, was identified. It was found that, as a result of Si mass transport to the Ge islands, the island/substrate interface moves towards the substrate, and trenches form on the substrate surface around the islands. Reduction of the misfit strain at the island/substrate interface is the driving force for this process. ͓S0163-1829͑99͒00748-1͔Semiconductor quantum dots ͑QD's͒ are attracting increasing interest because of their significant optoelectronic properties. 1 Although QD's can be produced in many ways, the method of coherent island formation is of great importance for materials with large lattice mismatch ͑such as Ge͑Si͒/Si 2,3 and In x Ga 1Ϫx As/GaAs 4 because of the possible combination of the QD growth and semiconductor integration techniques. Of crucial importance in determining the optoelectronic properties of the QD's are the structural parameters of the QD's including the shape, size and composition. 5 Uniformity in and control over these parameters are a prerequisite for many applications. To achieve this goal, a complete understanding of the mechanism of the QD growth is necessary. Although many investigations have concentrated on the shape and size 6,7 and evolution 8,9,10 during the QD growth, relatively less attention has been paid to the composition. 11,12,13 In the classical Stranski-Krastanow 14 ͑S-K͒ mode of coherent island formation, one material with a different lattice parameter and low interfacial energy is initially deposited on a substrate surface, layer by layer, forming a ''wetting layer''. When the wetting layer reaches a critical thickness ͓usually three to five monolayers for pure Ge on Si͑001͒, 3,15 island growth starts to partially release the mismatch strain energy between the epitaxial layer and the substrate. However, in the case of InAs/GaAs, recent investigations suggest that, for higher temperature growths, there is significant mass transport from both the wetting layer and the substrate to the islands. 16 Furthermore, the wetting layer in InAs/GaAs systems has been reported to be an ͑In,Ga͒As alloy with temperature dependent composition. 17 The composition of the alloy wetting layer will certainly affect any subsequent island growth procedure. These points suggest that the classical S-K growth mechanism needs to be modified to explain the details of island growth. In this paper, we demonstrate evidence for mass transport from the Si substrate to the Ge islands during high temperature molecular beam epitaxy ͑MBE͒ growth of ''pure'' Ge islands on the Si͑001͒ substrate. The mass transport changes the composition of the islands, moves the Ge/Si interface below the original substrate surface, and forms a trench around each island. It is proposed that the driving force for this mechanism is a reduction...

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Composition of InAs quantum dots on GaAs(001): Direct evidence for (In,Ga)As alloying

Cited by 307 publications

References 22 publications

Anisotropic diffusion of In adatoms on pseudomorphicInxGa1−xAsfilms: First-p

Anisotropic diffusion of In adatoms on pseudomorphicInxGa1−xAsfilms: First-p

Nanometer-Scale Resolution of Strain and Interdiffusion in Self-AssembledInAs/GaAsQuantum Dots

Strain relaxation by alloying effects in Ge islands grown on Si(001)

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