S. K. CHAUDHARY
Copyright © 2012 SciRes. CSTA
24
surrounded by a large number of vacancies should be
considered to be more mobile than others along the lay-
ers. Further, the density of vacancies and their distribu-
tion play an important role in semi conducting properties
of the materials. In a recent theoretical investigation Ito
et al. [12] have calculated that for SiC polytype with Si
vacancy, 6H structure is formed and 4H structure is fa-
vored in C vacancy condition. Thus showing that vacan-
cies in SiC play an important role in stabilizing a par-
ticular structure. Similar calculations have been made on
ZnS polytypic crystals [13].
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