Direct evidence of micropipe-related pure superscrew dislocations in SiC

Huang, Xianrong; Dudley, Michael; Vetter, William M.; Huang, Wei; Wang, S.; Carter, C. H.

doi:10.1063/1.123069

Cited by 114 publications

(84 citation statements)

References 10 publications

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“…In SiC, super screw dislocations and micropipes were successfully identified and analyzed by SR-XRT using a ray-tracing simulation technique. [116][117][118] The ray tracing simulation is based on dividing the area around the dislocation into a grid and calculating the position of the diffracted beam for each grid element, taking the local lattice distortion caused by the dislocation into account. The SR-XRT images of screw dislocations in SiC were found to be white circular features surrounded by a dark ring, and the radius was found to increase with increasing Burgers vector magnitude.…”

Section: Progress Reportmentioning

confidence: 99%

Defects in Single Crystalline Ammonothermal Gallium Nitride

Suihkonen

Pimputkar

Sintonen

et al. 2017

Adv Elect Materials

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Native bulk gallium nitride (GaN) has emerged as an alternative for sapphire and silicon as a substrate material for III‐N devices. While quasi‐bulk GaN substrates are currently commercially available, single crystal GaN substrates are considered essential for future high performance light emitters and power devices. The ammonothermal method is currently considered one of the most feasible methods to grow large truly bulk crystals of GaN at low cost and high structural quality. High crystalline quality GaN substrates sliced from ammonothermally grown crystals have been demonstrated and utilized in homoepitaxy for III‐N devices. However, despite the high crystalline quality the properties of as‐grown ammonothermal GaN crystals and substrates are affected by the presence of impurities and other defects that hinder their use for device applications. Here, the main developments of ammonothermal growth of GaN and the effects of impurities, native point defects, and dislocations on the material properties are summarized. Additionally, measurement techniques that enable the evaluation of point defect concentration and low dislocation density distribution over a large area on bulk GaN substrates are reviewed.

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Section: Progress Reportmentioning

confidence: 99%

Defects in Single Crystalline Ammonothermal Gallium Nitride

Suihkonen

Pimputkar

Sintonen

et al. 2017

Adv Elect Materials

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“…Apart from dislocations, micropipes ͑MPs͒, cylindrical pores that generally contain dislocations with giant Burgers vectors, 10 were frequently observed at the boundaries of polytype inclusions. [11][12][13] MPs were supposed to nucleate at low-angle boundaries between a polytype inclusion and a matrix.…”

Section: Introductionmentioning

confidence: 99%

Role of micropipes in the formation of pores at foreign polytype boundaries in SiC crystals

et al. 2007

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The role of micropipes in pore formation in SiC crystals with foreign polytype inclusions is studied by means of synchrotron phase sensitive radiography, optical and scanning electron microscopies, and color photoluminescence. The pores at the inclusion boundaries are revealed, and their shapes and locations are analyzed. It is found that the pores arise due to the attraction of micropipes by the foreign polytype interfaces, followed by micropipe coalescence. The observed pores have tubular or slit shapes. Tubular pores nucleate at the inclusion corners, where the inclusion-associated stresses are concentrated. Slit pores spread between them and follow the shape of the inclusion boundaries. We explain the observations within a two-dimensional model of elastic interaction between micropipes and inclusion boundaries, which accounts for free surfaces of micropipes.

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“…The problem was significantly simplified by an approximation based on a simple idea of summation of the contribution from a large number of point-like inclusions regularly distributed inside the volume of inclusion. This idea is justified by the principle of strain superposition, and the use of the formula given by Sen [11] enables taking into account the presence of the free surface. The representative contours of the effective change of reflecting condition computed with the revealed procedure are shown in Fig.…”

Section: Sin θ ∂U(r)mentioning

confidence: 99%

“…In particular, the applicability of the simple approximations of the extinction contrast is examined for screw dislocations perpendicular to the crystal surface in an arbitrary asymmetrical reflection, similarly as in [9]. The simulation of dislocation and rod-like inclusion images were applied for analysis of the Bragg-case section images in silicon carbide crystals, particularly to the images of pipe-formed cavities, suggested by Dudley and coworkers [10,11] as hollow-core super-screw dislocations. Some later papers [12][13][14] described, however, many cases when the strain fields around micro-pipes cannot be well described by that of hollow-core super--screw dislocation.…”

Section: Introductionmentioning

confidence: 99%

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The Simulation of Bragg-Case Section Images οf Dislocations and Inclusions in Aspect of Identification of Defects in SiC Crystals

2010

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The numerical simulation has been applied for studying of Bragg-case section topographic images of dislocation and rod-like inclusions. The validity of simple approximation of extinction contrast was confirmed in the case of screw dislocations in silicon carbide crystals. A procedure for approximate calculation of the strain field of rod-like inclusion was constructed, consisting of adding the contributions from a very large number of point-like inclusions uniformly distributed inside the assumed volume of the inclusion. The procedure ensured a reasonable similarity between the simulated topographs and experimental Bragg-case section topographic images of some pipe-formed cavities in silicon carbide crystals. The method is useful for some other materials, e.g. it enabled to compute realistic simulation of plane-wave topographs of the rod-like inclusions in YAG.

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Direct evidence of micropipe-related pure superscrew dislocations in SiC

Cited by 114 publications

References 10 publications

Defects in Single Crystalline Ammonothermal Gallium Nitride

Defects in Single Crystalline Ammonothermal Gallium Nitride

Role of micropipes in the formation of pores at foreign polytype boundaries in SiC crystals

The Simulation of Bragg-Case Section Images οf Dislocations and Inclusions in Aspect of Identification of Defects in SiC Crystals

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