Novel SiGe Island Coarsening Kinetics: Ostwald Ripening and Elastic Interactions

Floro, J. A.; Sinclair, Michael B.; Chason, E.; Freund, L. B.; Twesten, R. D.; Hwang, R. Q.; Lucadamo, G.

doi:10.1103/physrevlett.84.701

Cited by 125 publications

(91 citation statements)

References 22 publications

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“…When the film is infinitely thick or when the substrate is infinitely rigid, different theoretical [14,15] and numerical [16,17,18,19] approaches revealed finite-time singularities enforced by elastic stress concentration which account for experiments in thick films [8,9] where dislocations can finally develop. However, these models can not describe experiments of thin films in the Stranski-Krastanov type of growth [5,6] where the surface organizes smoothly into islands separated by a wetting layer and evolving with a coarsening dynamics under annealing [6]. A crucial issue for these systems is the wetting of the substrate by the film [20,21] which is a good candidate for regularizing the dynamics of the instability.…”

mentioning

confidence: 99%

“…for quantum dots, wires and electronic devices with specific confinement properties [4]. A notorious experimental example is Si/Ge films on a Si substrate which exhibit a variety of structures such as pre-pyramids, pyramids, domes and huts [5,6]. Such epitaxial films experience an elastic stress due to the misfit with the substrate which is relaxed by a morphological instability similar to the Asaro-Tiller-Grinfeld thermodynamical instability in solid-liquid interfaces [7].…”

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confidence: 99%

“…In fact, thanks to space and time rescaling, only ν f and ω * 2 /ω 2 are relevant for characterizing Eqs. (4) and (6). The wetting potential is described in an indicative way by c w = 0.05 and δ = 0.005.…”

mentioning

confidence: 99%

“…When c w = 0, the film is always linearly unstable and the nonlinear numerical computations exhibit generic finite-time blow-up solutions [22]. To analyze the nonlinear evolution in the presence of wetting effects, we performed numerical simulations using a pseudo-spectral method in a periodic box of length L. To be specific, we selected parameters depicting a Si 0.8 Ge 0.2 film on a Si substrate with ν f = 0.278, ω 1 = 2.44, ω 2 = 2.52 and ω * 2 = 2.34, leading to l 0 = 200 nm and with the value of the diffusion parameter D given in [13], t 0 = 8 hours at 750 • C, see [6]. In fact, thanks to space and time rescaling, only ν f and ω * 2 /ω 2 are relevant for characterizing Eqs.…”

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confidence: 99%

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Nonlinear evolution of a morphological instability in a strained epitaxial film

2007

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A strained epitaxial film deposited on a deformable substrate undergoes a morphological instability relaxing the elastic energy by surface diffusion. The nonlinear and nonlocal dynamical equations of such films with wetting interactions are derived and solved numerically in two and three dimensions. Above some critical thickness, the surface evolves towards an array of islands separated by a wetting layer. The island chemical potential decreases with its volume, so that the system experiences a non-interrupted coarsening described by power laws with a marked dimension dependence.PACS numbers: 81.15.Aa, 68.35.Ct The dynamics of semiconductor thin films is under active scrutiny due to its importance for both fundamental science and technological applications [1,2]. Indeed, thin film elastic instabilities lead to the self-organization of nanostructures [3] potentially useful e.g. for quantum dots, wires and electronic devices with specific confinement properties [4]. A notorious experimental example is Si/Ge films on a Si substrate which exhibit a variety of structures such as pre-pyramids, pyramids, domes and huts [5,6]. Such epitaxial films experience an elastic stress due to the misfit with the substrate which is relaxed by a morphological instability similar to the Asaro-Tiller-Grinfeld thermodynamical instability in solid-liquid interfaces [7]. This instability was first observed in experiments in helium at low temperature [8] and more generally in various solid interfaces [9,10,11].Although the evolution of epitaxial films involves many complex phenomena regarding surface energy, intermixing and kinetic processes, we focus here on the main effects ruling the dynamics of the morphological instability in strained films. The dynamics is ruled here by surface diffusion driven by the interplay between isotropic surface energy and elastic energy [12,13]. When the film is infinitely thick or when the substrate is infinitely rigid, different theoretical [14,15] and numerical [16,17,18,19] approaches revealed finite-time singularities enforced by elastic stress concentration which account for experiments in thick films [8,9] where dislocations can finally develop. However, these models can not describe experiments of thin films in the Stranski-Krastanov type of growth [5,6] where the surface organizes smoothly into islands separated by a wetting layer and evolving with a coarsening dynamics under annealing [6]. A crucial issue for these systems is the wetting of the substrate by the film [20,21] which is a good candidate for regularizing the dynamics of the instability. Indeed, crack singularities were circumvented near the instability threshold by considering slope dependent wetting effects [22]. However, the interplay between elastic relaxation, surface energy and wetting interactions is still under active study [23,24] and the description of the long term dynamics of the morphological instability in a thin strained film is an open issue. In this Letter, we present a model based on continuum elasticity which we ...

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confidence: 99%

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confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Nonlinear evolution of a morphological instability in a strained epitaxial film

2007

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“…An array of hut clusters selforders on a square mesh with increasing areal coverage. In case of a dense array of islands, Floro et al [61] found that ordering occurs to minimize the repulsive elastic interactions between neighbouring islands. However, self-organization breaks down when islands coalesce during deposition or static coarsening.…”

Section: Dense Arrays Of Islandsmentioning

confidence: 99%

Controlling the quantum dot nucleation site

Motta

Sgarlata

Rosei

et al. 2003

Materials Science and Engineering: B

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Thermal Properties and Heat Transport in Silicon‐Based Nanostructures

Chang

Tsybeskov

2010

Silicon Nanocrystals

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IntroductionFor the past 40 years, crystalline Si (c-Si) continues to be the major material for microelectronics, and modern silicon technology is superior compared to other semiconductors (e.g., II-VI and III-V compounds). In addition to the unique electronic and structural properties of bulk c-Si, silicon dioxide (SiO 2 ) and Si/SiO 2 interfaces, single-crystal Si possesses one of the best known lattice thermal conductivity [1,2]. This exceptional heat conductance is critically important for Si device heat management and circuit reliability. However, most of the modern complementary metal-oxide-semiconductor (CMOS) platforms are no longer single-crystal Si wafers but rather thin layers of Si-on-insulator (SOI), ultrathin strained Si and SiGe heterostructures that are the foundation of SiGe bipolar transistors (HBTs), and high-mobility metal-oxide-semiconductor field-effective transistors (MOSFETs). Major properties of these Si-based nanostructures are very different from those of bulk c-Si. For example, thermal conductivity in ultrathin SOI layers, SiGe alloys, and Si/SiGe nanostructures could be reduced by more than an order of magnitude compared to that in c-Si [3-6], and heat dissipation has become an important issue for modern nanoscale electronic devices and circuits. Thus, the understanding and improvement of heat management in Si-based nanostructures is critically important for the evolution of microelectronic industry.On the other hand, many interesting applications of nanostructured Si (ns-Si) in photonic devices and CMOS-compatible light emitters were recently discussed [7][8][9][10][11]. These ns-Si materials and devices can be produced by electrochemical anodization (i.e., porous Si [12]), chemical vapor deposition (CVD) using thermal decomposition of SiH 4 [13-15], Si ion implantation into a SiO 2 matrix [16], and deposition of amorphous Si/SiO 2 layers followed by thermal crystallization [17][18][19]. These ns-Si materials and devices produce an efficient and tunable light emission in the near-infrared and visible spectral region [20,21]. Also, it has been shown that under photoexcitation with energy density >10 mJ/cm 2 , optical gain is possibly Silicon Nanocrystals: Fundamentals, Synthesis and Applications. Edited by Lorenzo Pavesi and Rasit Turan

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Novel SiGe Island Coarsening Kinetics: Ostwald Ripening and Elastic Interactions

Cited by 125 publications

References 22 publications

Nonlinear evolution of a morphological instability in a strained epitaxial film

Nonlinear evolution of a morphological instability in a strained epitaxial film

Controlling the quantum dot nucleation site

Thermal Properties and Heat Transport in Silicon‐Based Nanostructures

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