Influence of the facet trace region in 4H-SiC substrate on the glide and propagation behaviors of basal plane dislocations in 4H-SiC homoepitaxial layers

Structure of the “carrot” defects in 4H-SiC homoepitaxial layers deposited by CVD has been investigated by plan-view and cross-sectional transmission x-ray topography, cross-sectional transmission electron microscopy, atomic force microscopy, and KOH etching. The carrot defects nucleate at the substrate/epilayer interface at the emergence points of threading screw dislocations propagating from the substrate. The typical defect consists of two stacking faults: one in the prismatic plane with second one in the basal plane. The faults are connected by a stair-rod dislocation with Burgers vector 1/n[10-10] with n>3 at the cross-over. The basal plane fault is of Frank-type. Carrot defects are electrically active as evidenced by contrast in EBIC images indicating enhanced carrier recombination rate. Presence of carrot defects in the p-i-n diodes results in higher pre-breakdown reverse leakage current and approximately 50% lower breakdown voltage compared to the nominal value.

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Structure and Origin of Carrot Defects on 4H-SiC Homoepitaxial Layers

Materials Science Forum ◽

10.4028/www.scientific.net/msf.778-780.354 ◽

2014 ◽

Vol 778-780 ◽

pp. 354-357 ◽

Cited By ~ 1

Author(s):

Lin Dong ◽

Guo Sheng Sun ◽

Jun Yu ◽

Guo Guo Yan ◽

Wan Shun Zhao ◽

...

Keyword(s):

Screw Dislocation ◽

Basal Plane ◽

Flow Direction ◽

Stacking Fault ◽

Threading Dislocation ◽

Step Flow ◽

Homoepitaxial Layers

A kind of broken carrot defects which are not parallel to the step flow direction are observed on 4H-SiC epilayer surfaces. We use the molten KOH and polishing methods to reveal the structure and source of the broken carrots. It is shown that the broken carrot defects still contain the prismatic stacking fault (SF) and basal plane SF and originate from threading screw dislocation on the substrate. The presence of other substrate threading dislocation can disturb the expansion of prismatic SF. This leads to the appearance of the broken carrot.

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Study of V and Y Shape Frank-Type Stacking Faults Formation in 4H-SiC Epilayer

Materials Science Forum ◽

10.4028/www.scientific.net/msf.778-780.332 ◽

2014 ◽

Vol 778-780 ◽

pp. 332-337 ◽

Cited By ~ 5

Author(s):

Huan Huan Wang ◽

Fang Zhen Wu ◽

Sha Yan Byrapa ◽

Yu Yang ◽

Balaji Raghothamachar ◽

...

Keyword(s):

Basal Plane ◽

Substrate Surface ◽

Geometric Analysis ◽

Stacking Faults ◽

Grazing Incidence ◽

Threading Dislocations ◽

X Ray ◽

Homoepitaxial Layers ◽

Surface Intersections ◽

Koh Etching

Nomarski optical microscopic, KOH etching and synchrotron topographic studies are presented of faint needle-like surface morphological features in 4H-SiC homoepitaxial layers. Grazing incidence synchrotron white beam x-ray topographs show V shaped features which transmission topographs reveal to enclose 1/4[0001] Frank-type stacking faults. Some of these V-shaped features have a tail associated with them and are referred to as Y-shaped defects. Geometric analysis of the size and shape of the V-shaped faults indicates that they are fully contained within the epilayer and appear to be nucleated at the substrate/epilayer interface. Detailed analysis shows that the positions of the V-shaped stacking faults match with the positions of c-axis threading dislocations with Burgers vectors of c or c+a in the substrate and thus appear to result from the deflection of these dislocations onto the basal plane during epilayer growth. Similarly, the Y-shaped defects match well with the substrate surface intersections of c-axis threading dislocations with Burgers vectors of c or c+a in the substrate which were deflected onto the basal plane during substrate growth. Based on the observed morphology of these defect configurations we propose a model for their formation mechanism.

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Studies of Relaxation Processes and Basal Plane Dislocations in CVD Grown Homoepitaxial Layers of 4H-SiC

ECS Transactions ◽

10.1149/06407.0213ecst ◽

2014 ◽

Vol 64 (7) ◽

pp. 213-222

Author(s):

H. Wang ◽

F. Wu ◽

Y. Yang ◽

J. Guo ◽

B. Raghothamachar ◽

...

Keyword(s):

Basal Plane ◽

Relaxation Processes ◽

Homoepitaxial Layers

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Observations of the Thermal Decomposition of Brucite

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101980 ◽

1968 ◽

Vol 26 ◽

pp. 446-447

Author(s):

P. L. Burnett ◽

W. R. Mitchell ◽

C. L. Houck

Keyword(s):

Thermal Decomposition ◽

Magnesium Oxide ◽

Basal Plane ◽

Magnesium Ions ◽

A Value ◽

Reaction Proceeds

Natural Brucite (Mg(OH)2) decomposes on heating to form magnesium oxide (MgO) having its cubic ﹛110﹜ and ﹛111﹜ planes respectively parallel to the prism and basal planes of the hexagonal brucite lattice. Although the crystal-lographic relation between the parent brucite crystal and the resulting mag-nesium oxide crystallites is well known, the exact mechanism by which the reaction proceeds is still a matter of controversy. Goodman described the decomposition as an initial shrinkage in the brucite basal plane allowing magnesium ions to shift their original sites to the required magnesium oxide positions followed by a collapse of the planes along the original <0001> direction of the brucite crystal. He noted that the (110) diffraction spots of brucite immediately shifted to the positions required for the (220) reflections of magnesium oxide. Gordon observed separate diffraction spots for the (110) brucite and (220) magnesium oxide planes. The positions of the (110) and (100) brucite never changed but only diminished in intensity while the (220) planes of magnesium shifted from a value larger than the listed ASTM d spacing to the predicted value as the decomposition progressed.

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The stability of dislocation networks under various oxygen-doping conditions in superconducting Bi2Sr2CaCu2Oy single crystals and their influence on the flux pinning properties

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100171742 ◽

1994 ◽

Vol 52 ◽

pp. 802-803

Author(s):

Y. Feng ◽

X. Y. Cai ◽

R. J. Kelley ◽

D. C. Larbalestier

Keyword(s):

Single Crystals ◽

Oxygen Content ◽

Basal Plane ◽

Flux Pinning ◽

Pinning Centers ◽

Before And After ◽

Anomalous Peak ◽

Basal Plane Dislocation ◽

The Stability ◽

Further Development

The issue of strong flux pinning is crucial to the further development of high critical current density Bi-Sr-Ca-Cu-O (BSCCO) superconductors in conductor-like applications, yet the pinning mechanisms are still much debated. Anomalous peaks in the M-H (magnetization vs. magnetic field) loops are commonly observed in Bi2Sr2CaCu2Oy (Bi-2212) single crystals. Oxygen vacancies may be effective flux pinning centers in BSCCO, as has been found in YBCO. However, it has also been proposed that basal-plane dislocation networks also act as effective pinning centers. Yang et al. proposed that the characteristic scale of the basal-plane dislocation networksmay strongly depend on oxygen content and the anomalous peak in the M-H loop at ˜20-30K may be due tothe flux pinning of decoupled two-dimensional pancake vortices by the dislocation networks. In light of this, we have performed an insitu observation on the dislocation networks precisely at the same region before and after annealing in air, vacuumand oxygen, in order to verify whether the dislocation networks change with varying oxygen content Inall cases, we have not found any noticeable changes in dislocation structure, regardless of the drastic changes in Tc and the anomalous magnetization. Therefore, it does not appear that the anomalous peak in the M-H loops is controlled by the basal-plane dislocation networks.

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Microstructure and Physical Properties of Clay-Polymer Composites

MRS Proceedings ◽

10.1557/proc-628-cc11.14 ◽

2000 ◽

Vol 628 ◽

Author(s):

T.N. Blanton ◽

D. Majumdar ◽

S.M. Melpolder

Keyword(s):

Composite Materials ◽

Physical Properties ◽

Polymer Composites ◽

Basal Plane ◽

X Ray Diffraction ◽

X Ray ◽

Layered Clay

ABSTRACTClay-polymer nanoparticulate composite materials are evaluated by the X-ray diffraction technique. The basal plane spacing provided information about the degree of intercalation and exfoliation of the 2: 1 layered clay structure. Both intercalation and exfoliation are controlled by the identity of the polymer and the clay:polymer ratio.

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