EXAFS characterisation of Ge nanocrystals in silica

Ridgway, Mark C; Azevedo, G. de M.; Glover, Christopher; Elliman, R. G.; Llewellyn, David J.; Cheung, A.; Johannessen, Bernt; Brett, D. A.; Foran, Garry J

doi:10.1016/j.nimb.2004.01.004

Cited by 16 publications

(13 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3 and previous report. 9 During this stage, Ge atoms diffuse throughout the layer and accumulate at the Si/ SiO 2 interface, consistent with the EDS results in Fig. 2͑b͒.…”

supporting

confidence: 87%

“…6 Charge storage in Ge-NC-based metal-oxide-semiconductor ͑MOS͒ structures is influenced by several mechanisms including quantum confinement/Coulomb blockade effects, and interface/defect states. 4,7 A number of groups have published reports on the structural properties of Ge NCs, 8,9 with the most detailed 9 providing important insight into the effect of annealing on the evolution of Ge nanocrystals. However, it is very important to investigate such behavior in the context of the present study, especially in relation to the influence of the SiO 2 / Si interface and the SiO 2 / metal contact in MOS structures which may directly affect the NVM characteristics.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Annealing temperature dependence of capacitance-voltage characteristics in Ge-nanocrystal-based nonvolatile memory structures

Park

Cho

Kim

et al. 2006

Journal of Applied Physics

View full text Add to dashboard Cite

The annealing temperature (TA) dependence of capacitance-voltage (C-V) characteristics has been studied in metal-oxide-semiconductor structures containing Ge nanocrystals (NCs) produced by ion implantation and annealing. These structures are of interest for application as nonvolatile memory and TA is shown to have a strong influence on the C-V hysteresis. This behavior is shown to be correlated with structural changes of the Ge NCs which have been characterized by synchrotron-radiation photoemission spectroscopy. Specifically, well-defined C-V characteristics with large hysteresis were found only for annealing temperatures greater than 950 °C where Ge nanocrystals are known to form. In this temperature regime, transmission electron microcopy and energy dispersive x-ray spectroscopy demonstrate the existence of regularly arranged Ge NCs of approximately 3–5 nm diameter located around 6.7 nm from the interface.

show abstract

“…3 and previous report. 9 During this stage, Ge atoms diffuse throughout the layer and accumulate at the Si/ SiO 2 interface, consistent with the EDS results in Fig. 2͑b͒.…”

supporting

confidence: 87%

mentioning

confidence: 99%

Annealing temperature dependence of capacitance-voltage characteristics in Ge-nanocrystal-based nonvolatile memory structures

Park

Cho

Kim

et al. 2006

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…Data were analyzed following the procedure described in Ref. 7. EXAFS spectra were isolated from the raw absorption by background subtraction and subsequent splining using SPLINE.…”

Section: Methodsmentioning

confidence: 99%

Ion-irradiation-induced preferential amorphization of Ge nanocrystals in silica

et al. 2005

View full text Add to dashboard Cite

Extended x-ray absorption fine structure ͑EXAFS͒ measurements have been used to characterize the ionirradiation-induced crystalline-to-amorphous phase transformation in Ge nanocrystals. The atomic-scale structure of Ge nanocrystals in a silica matrix is first shown to deviate from that of bulk crystalline material with an increase in both Gaussian and non-Gaussian forms of structural disorder. The magnitude of the disorder in the bond-length distribution is comparable to that of relaxed amorphous Ge. The amorphization of such nanocrystals is then demonstrated at an ion dose ϳ100 times less than that required for bulk crystalline material irradiated simultaneously. Specifically, Ge nanocrystals irradiated at −196°C are rendered amorphous at ϳ0.01 displacements per atom. Finally, we show the atomic-scale structure of amorphized nanocrystals and bulk amorphous material is comparable. The rapid amorphization of Ge nanocrystals is potentially the result of several factors including ͑i͒ the preferential nucleation of the amorphous phase at the nanocrystal/matrix interface, ͑ii͒ the preirradiation, higher-energy structural state of the nanocrystals themselves, ͑iii͒ an enhanced vacancy concentration within the nanocrystals due to inhibited Frenkel pair recombination when Ge interstitials are recoiled into the matrix, and ͑iv͒ ion-beam mixing and the subsequent increase in nanocrystal impurity concentrations.

show abstract

“…EXAFS yields atomic level, chemically selective local structural information on interatomic distances, disorder (both structural and thermal) and average coordination numbers (Rehr & Albers, 2000;Lee et al, 1981;Aksenov et al, 2001). As abundantly demonstrated in the literature (Kolobov et al, 2003;Cheung et al, 2004;Rockenberger et al, 1998;Ridgway et al, 2004;Modrow, 2004;Frenkel et al, 2001;Gilbert et al, 2004;Rockenberger et al, 1997;Araú jo et al, 2006;Araú jo, Giulian et al, 2008), EXAFS is particularly useful for the study of nanoparticles, given the typical photoelectron mean-free path of $10 Å , well matched to the dimensions of the NPs (Frenkel et al, 2001).…”

Section: X-ray Absorption Spectroscopymentioning

confidence: 96%

“…Firstly, the long-range order characteristic of crystalline materials is truncated as a result of their reduced dimensionality. Secondly, nanostructures tend to be highly disordered (Cheung et al, 2004;Rockenberger et al, 1998;Ridgway et al, 2004), given the lesser constraints on the positions of surface atoms owing to reduced coordination and/or interactions with the surrounding matrix. Hence, well established techniques developed for crystallography are of limited application (Billinge & Levin, 2007).…”

Section: Introductionmentioning

confidence: 99%

Investigation of indirect structural and chemical parameters of GeSi nanoparticles in a silica matrix by combined synchrotron radiation techniques

et al. 2011

View full text Add to dashboard Cite

The formation of GeSi nanoparticles on an SiO 2 matrix is studied here by synchrotron-based techniques. The shape, average diameter and size dispersion were obtained from grazing-incidence small-angle X-ray scattering data. X-ray diffraction measurements were used to obtain crystallite sizes and composition via resonant (anomalous) measurements. By using these techniques as input for extended X-ray absorption fine structure analysis, the local composition surrounding the Ge atoms is investigated. Although the results for each of the methods above are commonly analyzed separately, the combination of such techniques leads to an improved understanding of nanoparticle structural and chemical properties. Crucial indirect parameters that cannot be quantified by other means are accessed in this work, such as local strain, the possibility of forming core-shell structures, the fraction of Ge atoms diluted in the matrix (not forming nanoparticles), the amorphous and crystalline Ge fractions, and the relative population of nanoparticles with single and multiple crystalline domains.

show abstract

EXAFS characterisation of Ge nanocrystals in silica

Cited by 16 publications

References 9 publications

Annealing temperature dependence of capacitance-voltage characteristics in Ge-nanocrystal-based nonvolatile memory structures

Annealing temperature dependence of capacitance-voltage characteristics in Ge-nanocrystal-based nonvolatile memory structures

Ion-irradiation-induced preferential amorphization of Ge nanocrystals in silica

Investigation of indirect structural and chemical parameters of GeSi nanoparticles in a silica matrix by combined synchrotron radiation techniques

Contact Info

Product

Resources

About