Silicon carbide ingots grown by the modified Lely method on (0001)-plane are characterized by extremely developed defect structure. Thus, the study of non-basal plane growth of SiC became urgent for getting high quality non-basal substrates and further design of microelectronics devices as well as for so-called RAF-process and further getting defect-free (0001)-grown ingots. In this study the defect structure of the 4H-SiC crystals grown on (10-10), (11-20) and near to (8.3.-11.0) planes is considered. The last plane makes an angle of about 15^o with (10-10) and (11-20).

Initial 4H-SiC (10-10), (11-20) and (8.3.-11.0) substrates were cut from the single [000-1] grown crystal. The SiC crystal growth was held on these three seeds in the same growth experiment simultaneously. The grown ingot was cut into the wafers in three perpendicular directions: (10-10), (11-20) and (0001) cuts for [10-10]- and [11-20]-grown crystals and (8.3.-11.0), (-3 4 -1 0) and (0001) cuts for [8.3.-11.0]-grown crystal. Defect analysis was held using optical microscopy after KOH etching (type of defects was identified by etch pits form) as well as X-ray topography.

Defect structure of grown crystals is shown in fig. 1. It is well known that the growth on prismatic seeds leads to stacking faults (SF) formation (linear defect in fig. 1a)-1c)). We have found that SF formation probability strongly depends on seed crystallographic orientation and gradually increases with seed inclination from (11-20)-plane to (10-10)-plane. For [11-20]-grown crystal it was also noticed that SFs prevail on the edges of crystal where convex growth front has maximal inclination from initial (11-20)-plane. In spite of relatively low quantity of SFs the growth on (11-20) seed was characterized by formation of a huge number of basal plane dislocations (BPD).  The dissociation of these dislocations in (11-20)-plane with further SF formation is obviously impeded. So they keep being not dissociated during whole growth process.

Fig. 1d), f) and h) show (0001)-plane of grown crystals after KOH etching. This plane revealed BPDs as the only visible defect on the surface. The density of BPD is decreased from 4×10³ cm^-2 for [11-20] to 10³ cm^-2 for [10-10]. It is also clear that the inclination of the seed from (11-20)-plane to (10-10)-plane leads to merging of single BPDs and formation of low-angle grain boundaries (LAGB). 

Fig. 1e), g) and i) show the edges of the planes parallel to the growth direction and normal to (0001)-plane. There are multiple terraces on the etched substrates extended along growth direction. The number of these terraces is obviously depends on number of SFs. More SFs are in the growth plane, more and narrower terraces are in the plane normal to the last and (0001) one.

 Fig.1. a), b), c): cuts normal to the growth direction; d), f), h):  (0001)-plane; e), g), i): cuts parallel to the growth direction and normal to (0001)-plane for [11-20]-, [8.3.-11.0]- and [10-10]-grown crystals, respectively.

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1. Polytypism in SiC: theory and experiments