Superscrew dislocation contrast on synchrotron white-beam topographs: an accurate description of the direct dislocation image

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

doi:10.1107/s0021889899002939

Cited by 90 publications

(81 citation statements)

References 13 publications

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“…Screw dislocation contrast in symmetric 0008 back reflection SR-XRT was simulated using a geometrical approach adopted from previously reported successful SiC micropipe and super screw dislocation characterization. 18 of screw dislocations agree excellently with experimental images of dislocations in ammonothermal GaN. Defect selective etching (DSE) measurements support the SR-XRT results.…”

Section: Introductionsupporting

confidence: 73%

“…Examples of simulated GaN topograph TSD images are shown in Figure 2. The image of a threading screw dislocation consists of a white circular area surrounded by a dark contrast ring and is in appearance very similar to screw dislocations and micropipes found in SiC, 18,19,25 albeit smaller. The larger SiC dislocation image size is caused by differences in lattice constants and Burgers vectors.…”

Section: Theory and Image Simulationmentioning

confidence: 53%

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Synchrotron radiation x-ray topography and defect selective etching analysis of threading dislocations in GaN

Sintonen

Rudziński

Suihkonen

et al. 2014

Journal of Applied Physics

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The crystal quality of bulk GaN crystals is continuously improving due to advances in GaN growth techniques. Defect characterization of the GaN substrates by conventional methods is impeded by the very low dislocation density and a large scale defect analysis method is needed. White beam synchrotron radiation x-ray topography (SR-XRT) is a rapid and non-destructive technique for dislocation analysis on a large scale. In this study, the defect structure of an ammonothermal c-plane GaN substrate was recorded using SR-XRT and the image contrast caused by the dislocation induced microstrain was simulated. The simulations and experimental observations agree excellently and the SR-XRT image contrasts of mixed and screw dislocations were determined. Apart from a few exceptions, defect selective etching measurements were shown to correspond one to one with the SR-XRT results

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Section: Introductionsupporting

confidence: 73%

Section: Theory and Image Simulationmentioning

confidence: 53%

Synchrotron radiation x-ray topography and defect selective etching analysis of threading dislocations in GaN

Sintonen

Rudziński

Suihkonen

et al. 2014

Journal of Applied Physics

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“…12 Similar features are well known from SWXRT images of super-screw and hollow-core screw dislocations (micropipes) in SiC. 14,15 This kind of TSDs are also present here for the investigated HVPE-GaN crystal grown on an ammonothermal GaN-seed. The Fig.…”

Section: Large-area Back-reflection Topography Of Hvpe-gan Grown On Ansupporting

confidence: 80%

Synchrotron White-Beam X-Ray Topography Analysis of the Defect Structure of HVPE-GaN Substrates

Kirste

Danilewsky

Sochacki

et al. 2015

ECS J. Solid State Sci. Technol.

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The defect structure of HVPE-GaN crystals is examined using synchrotron white-beam X-ray topography (SWXRT) and topography results are interpreted and discussed in comparison to reciprocal lattice point broadening from high resolution X-ray diffraction (HRXRD) measurements. Two as-received commercial HVPE-GaN wafers from two different vendors and one HVPE-GaN which was grown on an ammonothermal GaN-seed are investigated in this study. To our knowledge SWXRT large area back-reflection analysis of HVPE-GaN grown on an ammonothermal GaN seed has been performed for the first time. From large-area topography the formation of a cellular defect network is identified for the commercial HVPE-GaN. Large differences in the crystal lattice misorientation deformation (mosaicity) are determined for the different samples by transmission section topography. For the HVPEGaN grown on an ammonothermal GaN-seed a very low defect density was ascertained. From the contrasts of the topography threading screw-type dislocations and threading mixed-type dislocations were identified. The X-ray topography analysis shows clearly and for the first time that the nature of the defect structure and the low density of ammonothermal GaN seeds can be transferred by HVPE growth of GaN. For demanding GaN-based (opto-)electronic applications such as laser diodes or transistors for high power electronics there is a need for material with low defect densities, since threading dislocations act as centers of non-radiative recombination, increasing the leakage current, reducing the room temperature mobility and so limiting the efficiency, performance and lifetime of devices. Freestanding GaN with low defect density is the substrate material of choice for the realization of such GaN-based device structures with superior properties. Different approaches for crystal growth of bulk GaN like ammonothermal growth, hydride vapor-phase epitaxy (HVPE) and high-and low-pressure solution growth were followed in recent years.1 The ammonothermal growth and HVPE seem to be the most promising methods to produce GaN substrates in sufficient number, size and material quality and substrates prepared with these growth methods have become available commercially in recent years. In the ammonothermal growth method, GaN crystalizes from a solution of Ga in supercritical ammonia with the addition of a mineralizer. For seed material, the ammonothermal growth method uses native GaN crystals. Benefits of the ammonothermal growth method are very low dislocation densities as low as 5 × 10 3 cm −2 and large curvature radii of the crystal planes (>100 m).2 Drawbacks of GaN ammonothermal growth method are the incorporation of impurities and the low growth rate (0.1 mm/day), even when the method can potentially produce hundreds of crystals in a single batch. In comparison, in HVPE the GaN crystallization takes place from the vapor phase by the reaction of ammonia with gallium chloride at temperatures of about 1050• C. HVPE uses GaN seed layers (templates) deposited e.g. by metalorganic v...

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“…The image of elementary screw dislocation can be simulated by ray-tracing method (Huang et al, 1999). As well known, for a screw dislocation along z axis, its displacement field can be described as …”

Section: Elementary Screw Dislocationsmentioning

confidence: 99%

Bulk Growth and Characterization of SiC Single Crystal

Ning¹

2011

Silicon Carbide - Materials, Processing and Applications in Electronic Devices

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Superscrew dislocation contrast on synchrotron white-beam topographs: an accurate description of the direct dislocation image

Cited by 90 publications

References 13 publications

Synchrotron radiation x-ray topography and defect selective etching analysis of threading dislocations in GaN

Synchrotron radiation x-ray topography and defect selective etching analysis of threading dislocations in GaN

Synchrotron White-Beam X-Ray Topography Analysis of the Defect Structure of HVPE-GaN Substrates

Bulk Growth and Characterization of SiC Single Crystal

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