Alloy decomposition during growth due to mobility differences

Venezuela, P.; Tersoff, J.

doi:10.1103/physrevb.58.10871

Cited by 54 publications

(51 citation statements)

References 10 publications

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“…Stability of such films have been considered previously both theoretically 5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22 and experimentally. The systems explored experimentally include SiGe 23,24,25,26,27,28,29 and InGaAs.…”

Section: Introductionmentioning

confidence: 99%

“…5,6,12,13 This consideration is based on recent experimental results of atomic mobilities on surface. E.g., the activation energy of step mobility for Ge on Ge(001) surface was measured to be smaller than that of Si on Si(001), 42 corresponding to much larger atomic mobility for Ge.…”

Section: Introductionmentioning

confidence: 99%

“…The dynamical equation for compositional perturbation at the surface can be determined by substituting energy formulae (5), (6) and (26) into Eq. (3).…”

mentioning

confidence: 99%

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Epitaxial growth in dislocation-free strained alloy films: Morphological and compositional instabilities

Huang

Desai

2002

Phys. Rev. B

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The mechanisms of stability or instability in the strained alloy film growth are of intense current interest to both theorists and experimentalists. We consider dislocation-free, coherent, growing alloy films which could exhibit a morphological instability without nucleation. We investigate such strained films by developing a nonequilibrium, continuum model and by performing a linear stability analysis. The couplings of film-substrate misfit strain, compositional stress, deposition rate, and growth temperature determine the stability of film morphology as well as the surface spinodal decomposition. We consider some realistic factors of epitaxial growth, in particular the composition dependence of elastic moduli and the coupling between top surface and underlying bulk of the film. The interplay of these factors leads to new stability results. In addition to the stability diagrams both above and below the coherent spinodal temperature, we also calculate the kinetic critical thickness for the onset of instability as well as its scaling behavior with respect to misfit strain and deposition rate. We apply our results to some real growth systems and discuss the implications related to some recent experimental observations.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Epitaxial growth in dislocation-free strained alloy films: Morphological and compositional instabilities

Huang

Desai

2002

Phys. Rev. B

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“…The relative importance of surface and bulk migration will depend upon the activation energies, but it is clear that some bulk migration is essential, even if only to provide Si to transport through the wetting layer. The lower mobility 26 of Si than Ge implies that while Ge can be transported from a longer distance, most of the Si consumed comes from areas surrounding the islands. This results in a trench around the island, as illustrated in Fig.…”

Section: Figmentioning

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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“…for SiGe, Ge diffusion is ∼10-100 times faster than Si at typical growth temperatures [217]) and depend on the local composition. This could induce kinetic segregation effects [208] and modify the film stability and evolution [218,219]. In Refs.…”

Section: Intermixingmentioning

confidence: 99%

Continuum modelling of semiconductor heteroepitaxy: an applied perspective

Bergamaschini

Salvalaglio

Backofen

et al. 2016

Advances in Physics: X

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Semiconductor heteroepitaxy involves a wealth of qualitatively different, competing phenomena. Examples include threedimensional island formation, injection of dislocations, mixing between film and substrate atoms. Their relative importance depends on the specific growth conditions, giving rise to a very complex scenario. The need for an optimal control over heteroepitaxial films and/or nanostructures is widespread: semiconductor epitaxy by molecular beam epitaxy or chemical vapour deposition is nowadays exploited also in industrial environments. Simulation models can be precious in limiting the parameter space to be sampled while aiming at films/nanostructures with the desired properties. In order to be appealing (and useful) to an applied audience, such models must yield predictions directly comparable with experimental data. This implies matching typical time scales and sizes, while offering a satisfactory description of the main physical driving forces. It is the aim of the present review to show that continuum models of semiconductor heteroepitaxy evolved significantly, providing a promising tool (even a working tool, in some cases) to comply with the above requirements. Several examples, spanning from the nanometre to the micron scale, are illustrated. Current limitations and future research directions are also discussed.

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Alloy decomposition during growth due to mobility differences

Cited by 54 publications

References 10 publications

Epitaxial growth in dislocation-free strained alloy films: Morphological and compositional instabilities

Epitaxial growth in dislocation-free strained alloy films: Morphological and compositional instabilities

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

Continuum modelling of semiconductor heteroepitaxy: an applied perspective

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