Extended defects in SiC and GaN semiconductors

SiC and GaN are examples of tetrahedrally-bonded semiconductors the structure of which can be simply described in terms of corner-sharing tetrahedra. Because such tetrahedra exist: in two variants, a multitude of structures with different crystal structures can exist that are called "polytypes". Thus, the common polytype of SiC is hexagonal 6H or 4H while the common polytype of GaN is 2H. Both these compounds, however, can also exist as a metastable, cubic, 3C polytype. In this paper, the structural aspects of a few extended defects, including line defects (dislocations) as well as planar defects, eg. {11 (2) over bar 0} prismatic stacking fault and inversion domain boundary (IDB), in SiC and GaN are discussed.