Premium
Dislocation Cores and Hardness Polarity of 4H‐SiC
Author(s) -
Ning XianJie,
Huvey Nicolas,
Pirouz Pirouz
Publication year - 1997
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1997.tb03033.x
Subject(s) - materials science , ribbon , dislocation , stacking fault , partial dislocations , crystallography , transmission electron microscopy , indentation , silicon , stacking , condensed matter physics , core (optical fiber) , molecular physics , composite material , chemistry , nanotechnology , metallurgy , physics , organic chemistry
The hardness of opposite basal faces of 4H‐SiC single crystals has been measured in the temperature range 25°‐1200°3C. A strong hardness anisotropy between the silicon‐terminated (0001) and carbon‐terminated (0001) faces of this polar crystal has been found. Transmission electron microscopy investigation of the dislocations in the plastic zone of the 1200°3C indentations shows that they lie predominantly on the basal planes parallel to the indented face, and the extra‐half planes of the nonscrew dislocations originate from the indented face. It is also found that, when the (0001) Si‐terminated face is indented, the dislocations are either widely dissociated, with the width of the stacking fault ribbon much larger than the equilibrium value, or else they are single leading partials, with the corresponding trailing partials absent. In this case, all the leading partials are found to have a silicon core. On the other hand, the dislocations in the plastic zone of the carbon‐terminated face are in the form of dissociated dislocations, with the width of the associated stacking fault ribbons appreciably less than the equilibrium value. Moreover, the leading partials of éhese dissociated dislocations have a carbon core. The results indicate that the hardness of the polar basal faces of 4H‐SiC at elevated temperatures is partly determined by the nature of the dislocation cores nucleated by the indentation process. It is argued that this is due to the influence of the core on the generation and glide of the leading partial dislocations.