Journal of Electron Microscopy 51:S265-S270 (2002)
© 2002 Oxford University Press
Full-length paper |
Atomic and electronic structure analysis of 
= 3 incoherent twin boundaries in ß-SiC
Interface Science Research Group, Special Division of Green Life Technology, AIST KANSAI, National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
To whom correspondence should be addressed. E-mail: koji.tanaka{at}aist.go.jp
The structures of 
= 3 incoherent twin boundaries in ß-SiC were studied by high-resolution electron microscopy (HREM), electron energy-loss spectroscopy (EELS), and theoretical calculation. Especially, the existence of the variety of structures of = 3 incoherent twin boundaries was found by HREM. All the observed = 3 incoherent twin boundaries consist of arrays of structural units composed of five-, six-, and seven-membered rings, although the kinds or features of structural units change according to the lengths or circumstances of the boundaries. It is shown from the tight-binding calculations that the grain boundary energy becomes lower when the reconstructed 
011
bonds are occupied by Si-Si bonds than C-C bonds. The grain boundary energy of the symmetrical structural unit composed of five-seven-six-membered rings is lower than that of the asymmetric one, however, the difference between those is small. EELS analysis indicated that C atoms exist at grain boundaries on the similar condition of grain interior. The observed results of HREM and EELS can be explained by the theoretical results.
Keywords ß-SiC, incoherent twin boundary, HREM, EELS, SCTB, first principles