Sublimation growth of silicon carbide bulk crystals: experimental and theoretical studies on defect formation and growth rate augmentation

1999 ◽  
Vol 198-199 ◽  
pp. 1005-1010 ◽  
Author(s):  
D Hofmann ◽  
M Bickermann ◽  
R Eckstein ◽  
M Kölbl ◽  
St.G Müller ◽  
...  
1998 ◽  
Vol 510 ◽  
Author(s):  
Noboru Ohtani ◽  
Jun Takahashi ◽  
Masakazu Katsuno ◽  
Hirokatsu Yashiro ◽  
Masatoshi Kanaya

AbstractThe defect formation during sublimation bulk crystal growth of silicon carbide (SiC) is discussed. SiC bulk crystals are produced by seeded sublimation growth (modified-Lely method), where SiC source powder sublimes and is recrystallized on a slightly cooled seed crystal at uncommonly high temperatures (≥2000°C). The crystals contain structural defects such as micropipes (hollow core dislocations), subgrain boundaries, stacking faults and glide dislocations in the basal plane. The type and density of the defects largely depend on the crystal growth direction, and many aspects are different between the growth parallel and perpendicular to the <0001> c-axis. Micropipes are characteristic defects to the c-axis growth, while a large number of stacking faults are introduced during growth perpendicular to the c-axis. We discuss the cause and mechanism of the defect formation


2010 ◽  
Vol 645-648 ◽  
pp. 375-378 ◽  
Author(s):  
Valdas Jokubavicius ◽  
Justinas Palisaitis ◽  
Remigijus Vasiliauskas ◽  
Rositza Yakimova ◽  
Mikael Syväjärvi

Different sublimation growth conditions of 3C-SiC approaching a bulk process have been investigated with the focus on appearance of macrodefects. The growth rate of 3C-SiC crystals grown on 6H-SiC varied from 380 to 460 μm/h with the thickness of the crystals from 190 to 230 μm, respectively. The formation of macrodefects with void character was revealed at the early stage of 3C-SiC crystal growth. The highest concentration of macrodefects appears in the vicinity of the domain in samples grown under high temperature gradient and fastest temperature ramp up. The formation of macrodefects was related to carbon deficiency which appear due to high Si/C ratio which is used to enable formation of the 3C-SiC polytype.


1996 ◽  
Vol 423 ◽  
Author(s):  
R. Eckstein ◽  
D. Hofmann ◽  
Y. Makarov ◽  
St. G. Müller ◽  
G. Pensl ◽  
...  

AbstractExperimental and numerical analysis have been performed on the sublimation growth process of SiC bulk crystals. Crystallographic, electrical and optical properties of the grown silicon carbide (SIC) crystals have been evaluated by various characterization techniques. Numerical models for the global simulation of SiC bulk growth including heat and mass transfer and chemical processes are applied and experimentally verified.


2000 ◽  
Vol 640 ◽  
Author(s):  
D. Schulz ◽  
J. Doerschel ◽  
K. Irmscher ◽  
H.-J. Rost ◽  
D. Siche ◽  
...  

ABSTRACTSublimation growth of 6H-SiC has been studied with respect to surface morphology, growth temperature, supersaturation and growth rate. Growth was performed on the C-terminated face of 6H seeds mainly and for comparison also the Si-terminated face was used. Step bunching is observed dependent on different parameters and is strongly influenced by the seed orientation. The growth rate of 4H on the C-face is found to be higher than the rate of 6H grown on the Siface.


1995 ◽  
Vol 409 ◽  
Author(s):  
E. Y. Sun ◽  
C. H. Hsueh ◽  
P. F. Becher

AbstractRising fracture resistance with crack extension (R-curve response) can lead to improvements in the mechanical reliability of ceramics. To understand how microstructures influence the R-curve behavior, direct observations of crack interactions with microstructural features were conducted on SiC whisker-reinforced alumina. The contribution of the dominant toughening mechanisms to the R-curve behavior of these composites is discussed using experimental and theoretical studies.


2020 ◽  
Author(s):  
Thomas Louis-Goff ◽  
Huu Vinh Trinh ◽  
Eileen Chen ◽  
Arnold L. Rheingold ◽  
Christian Ehm ◽  
...  

A new, efficient, catalytic difluorocarbenation of olefins to give 1,1-difluorocyclopropanes is presented. The catalyst, an organobismuth complex, uses TMSCF<sub>3</sub> as a stoichiometric difluorocarbene source. We demonstrate both the viability and robustness of this reaction over a wide range of alkenes and alkynes, including electron-poor alkenes, to generate the corresponding 1,1-difluorocyclopropanes and 1,1-difluorocyclopropenes. Ease of catalyst recovery from the reaction mixture is another attractive feature of this method. In depth experimental and theoretical studies showed that the key difluorocarbene-generating step proceeds through a bismuth non-redox synchronous mechanism generating a highly reactive free CF<sub>2</sub> in an endergonic pre-equilibrium. It is the reversibility when generating the difluorocarbene that accounts for the high selectivity, while minimizing CF<sub>2</sub>-recombination side-reactions.


2020 ◽  
Vol 12 (2) ◽  
pp. 02012-1-02012-5
Author(s):  
Dilip Maske ◽  
◽  
Manisha Deshpande ◽  
Dattatray Gadkari ◽  
◽  
...  

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