Origin of domain structure in hexagonal silicon carbide boules grown by the physical vapor transport method

Transmission electron microscopy (TEM), high-resolution X-ray diffraction, and KOH etching have been used to study the dislocation structure of 4H SiC crystals grown by the physical vapor transport method. Many of the etch pi ts on the Si(0 0 0 1) surface form arrays extending along the [(1) over bar 1 0 0] directions. Plan view conventional and high-resolution TEM show tha t the arrays consist of pure edge dislocations threading along the c-axis w ith identical Burgers vectors of the a/3[1 1 (2) over bar 0] type. The disl ocation arrays constitute low angle [0 0 0 1] tilt boundaries, i.e., [0 0 0 1] is the common axis lying in the boundary. Typical values of the misorie ntation are in the 60-200 arcsec range. Evidence is presented that such bou ndaries can form by polygonization of the threading edge dislocations, whic h have been introduced into SiC crystals by prismatic slip. (C) 2000 Publis hed by Elsevier Science B.V.