Analysis of the extended defects in 3C-SiC.pdf - Nelson Mandela ...
Analysis of the extended defects in 3C-SiC.pdf - Nelson Mandela ...
Analysis of the extended defects in 3C-SiC.pdf - Nelson Mandela ...
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86<br />
(a) (b)<br />
Fig. 7.14. (a) Bright-field TEM micrograph <strong>of</strong> <strong>the</strong> bulk <strong>of</strong> <strong>the</strong> <strong>3C</strong>- <strong>SiC</strong> sample<br />
annealed at 1600°C for 1 hr. (b) Bright field micrograph show<strong>in</strong>g dislocation<br />
complexes <strong>in</strong> <strong>3C</strong>-<strong>SiC</strong> sample annealed at 1600°C for 1 hr. B = [111], g = 220, s ≥0.<br />
The dislocation complexes seen <strong>in</strong> Fig. 7.14 (b) were <strong>in</strong>itially not observed <strong>in</strong> <strong>the</strong><br />
unimplanted sample and it was <strong>in</strong>itially thought that <strong>the</strong>y might have formed due to<br />
ei<strong>the</strong>r <strong>the</strong> irradiation or anneal<strong>in</strong>g process. This was found not to be <strong>the</strong> case s<strong>in</strong>ce a<br />
reassessment (Section 7.3) <strong>of</strong> <strong>the</strong> unimplanted sample <strong>in</strong> <strong>the</strong> {111} beam direction<br />
showed similar defect complexes.<br />
Fur<strong>the</strong>rmore an electron diffraction <strong>in</strong>vestigation was done to confirm that no phase<br />
change occurred dur<strong>in</strong>g <strong>the</strong> anneal<strong>in</strong>g <strong>of</strong> <strong>the</strong> sample at 1600°C. A diffraction pattern<br />
<strong>of</strong> <strong>the</strong> zone axis was taken and matched with simulated patterns. This was done<br />
for <strong>the</strong> s<strong>in</strong>ce this direction allows an unambiguous differentiation between<br />
cubic and hexagonal <strong>SiC</strong> phases. Excellent agreement was found and it was<br />
concluded that <strong>the</strong> crystal structure rema<strong>in</strong>ed that <strong>of</strong> <strong>the</strong> cubic <strong>3C</strong> phase. The results<br />
are shown <strong>in</strong> Fig. 7.15.