Polytypic transformations in silicon carbide

Jepps, N. W.; Page, T. F.

doi:10.1016/0146-3535(83)90034-5

Cited by 232 publications

(116 citation statements)

References 50 publications

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“…This indicates that the step bunching is more pronounced in the 8 off 4H-SiC surface than in the 3:5 off 6H-SiC surface as indicated by the height, N, of the bunched step; N 4 for 4H-SiC and N 1 for 6H-SiC, where N is in a unit of one-unit cell of each polytype. Note that the stable surface after bunching is always ABA 0 C 0 in 4H and A of ABCA 0 C 0 B 0 in 6H, where ABC denotes the classical notation of the stacking sequence of SiC polytypes [23]. This is possibly a result of surface energy variation in each plane as predicted by Cheng et al [24] and Chien et al [25].…”

mentioning

confidence: 83%

Self-Ordering of Nanofacets on Vicinal SiC Surfaces

2003

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Vicinal 4H and 6H-SiC 0001 surfaces have been investigated using atomic force microscopy and cross-sectional high-resolution transmission electron microscopy. We observed the characteristic selfordering of nanofacets on any surface, regardless of polytypes and vicinal angles, after gas etching at high temperature. Two facet planes are typically revealed: (0001) and high index 112n that are induced by equilibrium surface phase separation. A 112n plane may have a free energy minimum due to attractive step-step interactions. The differing ordering distances in 4H and 6H polytypes imply the existence of SiC polytypic dependence on nanofaceting. Thus, it should be possible to control SiC surface nanostructures by selecting a polytype, a vicinal angle, and an etching temperature.

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confidence: 83%

Self-Ordering of Nanofacets on Vicinal SiC Surfaces

2003

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“…In our case P-T conditions were fairly constant and should have played only a minor role if any. Simultaneous development of several polytypes could occur due to variations in Si/C ratio in the growth system and due to inhomogeneous impurity incorporation [3,4]. Si/C ratio in the growth medium is important for at least two main reasons: (a) the composition of polytypes shows slight variations in Si/C ratio [27]; and (b) changes in the concentration of carbon or silicon vacancies influences SiC hexagonality [5,28].…”

Section: Discussionmentioning

confidence: 99%

“…Pressure and temperature during crystal growth both play important roles determining which polytype is produced [2]. It has also been suggested that impurities and intrinsic defects may influence the stability of polytypes ( [3][4][5] and references therein). Additional information contributing to the understanding of polytypes formation is of considerable applied and basic interest.…”

Section: Introductionmentioning

confidence: 99%

Isotopic heterogeneity in synthetic and natural silicon carbide

Shiryaev

Wiedenbeck

Reutsky

et al. 2008

Journal of Physics and Chemistry of Solids

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The distribution of both carbon and silicon isotopes in synthetic sublimation growth SiC wafers and in natural SiC grains was studied using secondary ion mass-spectrometry (SIMS).Significant variations in both isotopic ratios were observed which were broadly correlated with the crystalline perfection as documented by Raman microspectroscopy. Domains consisting of 15R (or with its admixture) are, on average, enriched in 12 C isotope relative to 6H domains, and they also show larger scatter in their observed silicon isotope ratios. We ascribe such heterogeneity to fluctuations of Si/C ratio in the growth medium and it is possible to model the spatial extent of such fluctuations. For the natural SiC grains the isotopic data suggest that they grew under relatively stable conditions, although some of them show significant isotopic zoning.

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“…More than 180 different polytypes are known [8] The most common polytypes are 3C (cubic), 4H (hexagonal), 6H (hexagonal) and 15R (rhombohedral). The 3C polytype, also called β-SiC phase, is stable at lower temperatures (below 2000 °C) [8][9][10] showing globular grains with low fracture toughness and high hardness. The α-SiC phase that include all polytypes presenting hexagonal or rhombohedral symmetries is stable at higher temperatures, above 2000 °C.…”

Section: Introductionmentioning

confidence: 99%

Structural characterization of liquid phase sintered silicon carbide by high-resolution X-ray diffractometry

et al. 2005

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Silicon carbide (SiC) was sintered using two different additives: AlN-Y 2 O 3 or AlN-CRE 2 O 3 . CRE 2 O 3 is a mixed oxide formed by Y 2 O 3 and rare-earth oxides. The crystalline structures of the phases were analyzed by high-resolution X-ray diffraction using synchrotron light source. The results of the Rietveld refinement of the mixed oxide show a solid solution formation. In both silicon carbide samples prepared using AlN-Y 2 O 3 or AlN-CRE 2 O 3 3C (β-phase) and 6H (α-phase) polytypes were found. The structural and microstructural results for both samples were similar. This is an indication of the viability of the use of CRE 2 O 3 in substitution for Y 2 O 3 as additive to obtain dense materials.

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Polytypic transformations in silicon carbide

Cited by 232 publications

References 50 publications

Self-Ordering of Nanofacets on Vicinal SiC Surfaces

Self-Ordering of Nanofacets on Vicinal SiC Surfaces

Isotopic heterogeneity in synthetic and natural silicon carbide

Structural characterization of liquid phase sintered silicon carbide by high-resolution X-ray diffractometry

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