SiGe intermixing in Ge/Si(100) islands

Capellini, Giovanni; Seta, M. De; Evangelisti, F.

doi:10.1063/1.1339263

Cited by 170 publications

(106 citation statements)

References 21 publications

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“…Qualitatively similar experimental results (exhibiting highly alloyed nanostructures, especially in the lower and central parts of the islands) have been also obtained by other authors using different experimental techniques [50,[52][53][54][55][56][57][58].…”

Section: Experimental Results Reporting Si-rich Coressupporting

confidence: 74%

Alloying of self-organized semiconductor 3D islands

Ratto

Costantini

Rastelli

et al. 2006

Journal of Experimental Nanoscience

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We present a short review of alloying in uncapped self-organized semiconductor heteronanostructures. Our aim is to provide a logical guide through the main concepts proposed in recent scientific debates. In particular, we focus on the issue of mapping the chemical composition within individual germanium quantum dots grown on silicon surfaces, a widely studied model system with high technological potential. We discuss the different experimental results reported so far in the literature, along with the main theories suggested for their rationalization. In particular, we expand on the interplay of competing factors, including thermodynamic considerations, strain relaxation and kinetic limitations. Finally, we propose a possible pathway towards a unifying picture, with the intention to motivate further research on this topic.

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Section: Experimental Results Reporting Si-rich Coressupporting

confidence: 74%

Alloying of self-organized semiconductor 3D islands

Ratto

Costantini

Rastelli

et al. 2006

Journal of Experimental Nanoscience

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“…ε m = (a(c s )−a(c f ))/a(c f ) ≈ χε 0 (with ε 0 the misfit between the pure components). According to the ATG model (Section 2.3), this results into different critical wavelengths for the film instability: the smaller is χ the longer is the unstable wavelength, in agreement with the experimental observation of larger islands when considering diluted alloys [28]. A variation in the surface energy density γ is also expected when changing the film composition but the effect of the misfit is assumed to be dominant (q c ∼ ε 2 m /γ ).…”

Section: Intermixingsupporting

confidence: 63%

“…Experimental evidences [28,29] clearly show the occurrence of a complex intermixing dynamics during the growth process which implies both non-uniform composition profiles [205] and time dependence of the composition field. In order to account for these effects, an excess contribution must be included in the definition of the system free energy: G mix = H mix − TS mix .…”

Section: Intermixingmentioning

confidence: 99%

“…Actually, despite being favoured by entropy, intermixing is yet another channel leading to strain relaxation as alloying lowers the effective lattice mismatch between film and substrate [25,26]. Intermixing becomes of particular importance at high temperatures, when deposited atoms can easily exchange position with the substrate ones [27,28]. Possible consequences involve the formation of a wetting layer not uniquely composed of the deposited material, and/or 3D islands hosting a significant concentration of substrate atoms.…”

Section: Introductionmentioning

confidence: 99%

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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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“…The relatively large lattice mismatch (4.2%) and thermal expansion coefficient (TEC) mismatch (130%) often lead to the introduction of dislocations and cracks. In addition, there is the strain-driven and surface energy-driven Ge-Si interdiffusion 7 causing difficulty in the control of the resulting heterostructure.…”

Section: Introductionmentioning

confidence: 99%

Photodetection in Hybrid Single-Layer Graphene/Fully Coherent Germanium Island Nanostructures Selectively Grown on Silicon Nanotip Patterns

Niu

Capellini

Łupina

et al. 2016

ACS Appl. Mater. Interfaces

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Dislocation networks are one of the most principle sources deteriorating the performances of devices based on lattice-mismatched heteroepitaxial systems. We demonstrate here a technique enabling fully coherent Ge islands selectively grown on nano-tip patterned Si (001) substrates. The Si-tip patterned substrate, fabricated by complementary metal-oxidesemiconductor (CMOS) compatible nanotechnology, features ~50 nm wide Si areas emerging from a SiO 2 matrix and arranged in an ordered lattice. Molecular beam epitaxy (MBE) growths result in Ge nano-islands with high selectivity and having homogeneous shape and size. The ~850°C growth temperature required for ensuring selective growth has been shown to lead to the formation of Ge islands of high crystalline quality without extensive Si intermixing (with 91 at.% Ge). Nano-tip patterned wafers result in geometric, kinetic diffusion barrier intermixing hindrance confining the major intermixing to the pedestal region of Ge islands where kinetic diffusion barriers are however high. Theoretical calculations suggest that the thin SiGe layer at the interface plays nevertheless a significant role in realizing our fully coherent Ge nano-islands free from extended defects especially dislocations. Single layer graphene (SLG)/Ge/Si-tip Schottky junctions were fabricated and thanks to the absence of extended defect in Ge islands, they demonstrate high performance photodetection characteristics with responsivity and I on /I off ratio of ~45 mA/W and ~10 3 , respectively.

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SiGe intermixing in Ge/Si(100) islands

Cited by 170 publications

References 21 publications

Alloying of self-organized semiconductor 3D islands

Alloying of self-organized semiconductor 3D islands

Continuum modelling of semiconductor heteroepitaxy: an applied perspective

Photodetection in Hybrid Single-Layer Graphene/Fully Coherent Germanium Island Nanostructures Selectively Grown on Silicon Nanotip Patterns

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