Properties of GeSi Nanocrystals Embedded in Hexagonal SiC

Kaiser, Ute; Biskupek, Johannes; Muller, David A.; Gärtner, K.; Schubert, C.

doi:10.1002/1521-4079(200204)37:4<391::aid-crat391>3.0.co;2-y

Cited by 16 publications

(9 citation statements)

References 39 publications

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“…Molecular dynamics calculations for hexagonal and cubic Ge nanocrystals embedded in either hexagonal or cubic SiC show that the matrix structure affects the nanocrystal structure 42 . As can be seen from Fig.…”

Section: Why Are Gesi Nanocrystals Hexagonal ?mentioning

confidence: 95%

“…ErSi 2 -nanocrystals (identified from HRTEM studies 40 ) are always found in the same orientation relationship and with the same bell-like shape, which is associated with the 0004C surfaces of the SiC matrix. In contrast, the nanocrystals created after Ge implantation, have different shapes and show different orientation relationships 39,42 .…”

Section: Properties Of Embedded Nanocrystals Created After Ge and Er mentioning

confidence: 99%

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Advanced transmission electron microscopy for nano-optics

Kaiser

2003

SPIE Proceedings

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Section: Why Are Gesi Nanocrystals Hexagonal ?mentioning

confidence: 95%

Section: Properties Of Embedded Nanocrystals Created After Ge and Er mentioning

confidence: 99%

Advanced transmission electron microscopy for nano-optics

Kaiser

2003

SPIE Proceedings

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“…This allowed a detailed analysis of the shape and faceting of the particles as well as determination of the crystallographic orientation of the erbium decorated dislocation loops. These results will be compared to initial data obtained by discrete tomography.In 2D, the nucleation, growth and structure of these clusters and nanocrystals have already been studied by Kaiser and coworkers using HRTEM and Z-contrast imaging [2][3][4]. Viewed along the [11][12][13][14][15][16][17][18][19][20] SiC projection, the ErSi 2 nanocrystals exhibit a characteristic hill-like shape with a welldefined flat base along the (0001) SiC basal plane [2].…”

mentioning

confidence: 99%

“…This variation of the 3D orientation confirms earlier calculations, which indicated several energy minima for a rotation of a Ge x Si 1-x crystal within a SiC matrix [3]. Nevertheless, for the first time, clear similarities between the shape of the ErSi 2 and Ge x Si 1-x could be observed.…”

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confidence: 99%

Electron Tomographic Characterization of ErSi2 and GexSi1-x Nanoparticles Prepared by Doping of 4H-SiC

Kuebel

Kaiser

2006

Microsc Microanal

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Small semiconductor or transition metal crystals embedded in a semiconducting matrix are nanostructured systems with interesting new properties in fields such as optics and spintronics. Ge nanocrystals embedded in SiC are, for instance, a promising system for optically active quantum dots. In addition to their size, composition and strain, their electronic structure strongly depends on their shape [1]. We have studied the 3D structure of Ge x Si 1-x and ErSi 2 nanocrystals formed after high dose Ge and Er ion implantation in 4H-SiC, respectively, by HAADF-STEM tomography. Using continuous iterative reconstruction techniques, it was not only possible to visualize the nanoparticles with a diameter of 1-25 nm, but also erbium decorated voids and dislocation loops could be imaged in 3D. This allowed a detailed analysis of the shape and faceting of the particles as well as determination of the crystallographic orientation of the erbium decorated dislocation loops. These results will be compared to initial data obtained by discrete tomography.In 2D, the nucleation, growth and structure of these clusters and nanocrystals have already been studied by Kaiser and coworkers using HRTEM and Z-contrast imaging [2][3][4]. Viewed along the [11][12][13][14][15][16][17][18][19][20] SiC projection, the ErSi 2 nanocrystals exhibit a characteristic hill-like shape with a welldefined flat base along the (0001) SiC basal plane [2]. Further faceting of these nanocrystals only becomes visible in 3D. We found that their basal plane typically exhibits strong hexagonal faceting corresponding to the {1-10l} class planes in SiC (Figure 1). Both their shape and orientation stay the same throughout most of the sample; only occasionally nanocrystals also exhibiting {11-2l} type facets are observed. Many of the nanocrystals are intersected by erbium decorated dislocation loops, which are typically oriented along the <1-100> direction in SiC (Figure 2).

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“…After annealing, the compressive strain relaxed to a stable magnitude up to at least 1650°C, while the thickness fringes indicated the layer remained pseudomorphic. 12 The broad SADP spot near the top of the as-implanted sample indicated amorphization near the surface, or disorder within the 4H stacking sequence, which was unresolved by TEM, and may be associated with the IR reflection peak near 948 cm −1 . 8 Figure 5(b) shows that, for annealing T A ജ 1250°C, the disorder mode near 948 cm −1 disappeared, but the 4H-FTO stacking mode at 838 cm −1 increased in strength to 1450°C, suggesting that the annealed layers were 4H.…”

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confidence: 99%

Pseudomorphic SiC alloys formed by Ge ion implantation

Dashiell

Xuan

Ansorge

et al. 2004

Applied Physics Letters

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Pseudomorphic-strained layers containing from 0.07-1.25 atomic % Ge were formed by ion implantation at 1000°C into 4H-SiC substrates. X-ray diffraction revealed high crystalline quality and coherent interfaces for strains up to 1.4%. Infrared reflectivity indicated a phonon mode at 948 cm −1 , attributed to Ge implantation disorder. Annealing above 1250°C caused the disappearance of the 948 cm −1 disorder mode, and the strengthening of the phonon mode at 848 cm −1 , associated with the 4H stacking sequence. Structural measurements of the annealed samples revealed thermally stable, coherently strained layers of the 4H polytype, without precipitation, suggesting an isoelectronic Ge alloy compatible with SiC for heterostructure strained layer engineering.

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Properties of GeSi Nanocrystals Embedded in Hexagonal SiC

Cited by 16 publications

References 39 publications

Advanced transmission electron microscopy for nano-optics

Advanced transmission electron microscopy for nano-optics

Electron Tomographic Characterization of ErSi2 and GexSi1-x Nanoparticles Prepared by Doping of 4H-SiC

Pseudomorphic SiC alloys formed by Ge ion implantation

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