Evolution of nanocluster ensembles: Computer simulation of diffusion and reaction controlled Ostwald ripening

Strobel, Matthias; Reiss, S.; Heinig, Karl-Heinz

doi:10.1016/s0168-583x(96)00512-5

Cited by 17 publications

(4 citation statements)

References 7 publications

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“…15 Following implantation, samples were annealed in flowing forming gas ͑5%H 2 +95%N 2 ͒ for 1 h at temperatures of 500, 800, and 1100°C to induce Cu precipitation and NC growth. 16 Rutherford backscattering spectroscopy ͑RBS͒ was performed with 4.2-MeV He 2+ ions and a surface-barrier detector oriented at a scattering angle of 168°. This enabled investigation of the implantation profile to a depth of ϳ2 m to probe the Cu concentration before and after thermal annealing.…”

Section: Methodsmentioning

confidence: 99%

Structural characterization of Cu nanocrystals formed in SiO2 by high-energy ion-beam synthesis

Johannessen

Kluth

Glover

et al. 2005

Journal of Applied Physics

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Cu nanocrystals ͑NCs͒ were produced by multiple high-energy ion implantations into 5-m-thick amorphous silica ͑SiO 2 ͒ at liquid-nitrogen temperature. The Cu-rich SiO 2 films were subsequently annealed to reduce irradiation-induced damage and promote NC formation. The NC size distribution and structure were studied utilizing a combination of Rutherford backscattering spectroscopy, x-ray diffraction, cross-sectional transmission electron microscopy, and extended x-ray-absorption fine-structure ͑EXAFS͒ spectroscopy. We present results derived from all four techniques, focussing on EXAFS measurements to study the local atomic structure surrounding Cu atoms, and comparing NC samples with bulk standards. Using a unique sample preparation method, we drastically improve the signal-to-noise ratio to extract high-quality EXAFS data to enable the determination of a non-Gaussian bond length distribution via the third-order cumulant. We quantify subtle concentration-and annealing-temperature-dependent changes in the Cu NC short-range order and relate such changes to NC size. Relative to a bulk Cu standard, enhanced structural disorder is observed in addition to both a suppressed coordination number and bond length contraction. Deviations from bulklike structure increase as the NC size decreases. Samples of low Cu concentration and/or low annealing temperature contain a significant fraction of Cu oxides, as either oxidized NCs or Cu bonding to O in the SiO 2 matrix. EXAFS and x-ray-absorption near-edge structure analyses demonstrate Cu in an oxidized form exhibits an oxidation state and local coordination similar to crystalline Cu 2 O albeit in a disordered form.

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Section: Methodsmentioning

confidence: 99%

Structural characterization of Cu nanocrystals formed in SiO2 by high-energy ion-beam synthesis

Johannessen

Kluth

Glover

et al. 2005

Journal of Applied Physics

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“…The depth of surface chemistry is controlled by the diffusion length of the oxidant into SiO 2 and the screening length of the clusters in the nanocluster band. 19 The first direct evidence for the appearance of bands containing nanocrystalline Ge clusters within a SiO 2 matrix and the influence of interface reactions and surface chemistry is of significant importance for the fabrication of layers with a well controlled cluster distribution for electroluminescing applications. The results obtained are also interesting from a fundamental point of view as they demonstrate that Ostwald ripening can occur in materials with low diffusion rates.…”

mentioning

confidence: 99%

Multimodal impurity redistribution and nanocluster formation in Ge implanted silicon dioxide films

Borany

Grötzschel

Heinig

et al. 1997

Applied Physics Letters

104

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The depth distribution of Ge implanted into thermally grown SiO2 films has been studied after annealing using transmission electron microscopy, Rutherford backscattering spectrometry, and x-ray diffraction. At annealing temperatures above 900 °C a significant redistribution of the as-implanted Ge profile was found. Crystalline Ge nanoclusters embedded in the SiO2 matrix are formed within a cluster band with well defined boundaries. The evolution of nanoclusters can be explained qualitatively by a model based on nucleation, growth and Ostwald ripening of Ge precipitates. Besides, chemical and interface reactions lead to the formation of additional Ge peaks near the surface and at the Si/SiO2 interface.

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“…During OR, small clusters of atoms/molecules dissolve, transferring their mass to bigger clusters. Classical mean-field treatment of OR [9][10][11][12][13][14] predicts a steady-state growth regime with the average cluster size hRi increasing in time as hRi t 1 > > 0, which is confirmed in numerical [8,[15][16][17][18][19] and experimental [4 -7,20 -24] investigations of the systems satisfying the theoretical assumptions. All theoretical studies of OR performed so far are confined to the case when the mean free path of molecules in a vapor/solution is small compared to the minimum cluster size.…”

mentioning

confidence: 67%

Ostwald Ripening in Rarefied Systems

Burlakov

2006

Phys. Rev. Lett.

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Mass exchange between spherical molecular clusters is analyzed in the case when the mean free path of molecules in the intercluster space is much larger than the cluster sizes but much smaller than average intercluster separation. It is shown that there is a steady-state regime when big clusters grow at the expense of the smaller ones (Ostwald ripening), which is characterized by a one-parametric family of self-similar cluster size distribution functions and by an exponentially growing average cluster size. The obtained self-similar cluster size distributions are entirely different from those given by the classical theory of Ostwald ripening. Implications of the obtained results are discussed.

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Evolution of nanocluster ensembles: Computer simulation of diffusion and reaction controlled Ostwald ripening

Cited by 17 publications

References 7 publications

Structural characterization of Cu nanocrystals formed in SiO2 by high-energy ion-beam synthesis

Structural characterization of Cu nanocrystals formed in SiO2 by high-energy ion-beam synthesis

Multimodal impurity redistribution and nanocluster formation in Ge implanted silicon dioxide films

Ostwald Ripening in Rarefied Systems

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