Dislocation cores and hardness polarity of 4H-SiC
- Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Materials science and Engineering
The hardness of opposite basal faces of 4H-SiC single crystals has been measured in the temperature range 25--1,200 C. A strong hardness anisotropy between the silicon-terminated (0001) and carbon-terminated (000{bar 1}) faces of this polar crystal has been found. Transmission electron microscopy investigation of the dislocations in the plastic zone of the 1,200 C 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 these 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.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-93ER45496
- OSTI ID:
- 529530
- Journal Information:
- Journal of the American Ceramic Society, Vol. 80, Issue 7; Other Information: DN: Paper presented at the symposium on microstructure-property relations of advanced materials, April 29--30, 1996, Stuttgart (DE); PBD: Jul 1997
- Country of Publication:
- United States
- Language:
- English
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