CVD Si3N4 on single crystal SiC: Part II. High resolution electron microscopy and atomic models of the interface

Abstract

Interface studies of CVD Si3N4 grown on (11$\overline 1$) SiC single crystal substrates have been made by transmission electron microscopy (TEM). It is found that there are two orientation relationships both of which involve the same (10$\overline 1$0)Si3N4//(11$\overline 1$)SiC planar relationship. However, the orientation relationships are not perfect and rotations of 2–6° are commonly seen between both directions and planes involved. High resolution electron microscopy (HREM) of the interfaces shows that the SiC and Si3N4 are continuous up to the interface and that no intermediate phases are formed. However, due to the small rotations, the HREM images are difficult to interpret directly in terms of atomic positions. Nevertheless, possible atomic models of the interface are proposed based upon the experimental findings. These models exploit the similarities between the [SiN4] and [SiC4] tetrahedra in Si3N4 and SiC, respectively. The observed orientation relationships appear to be due to matching of tetrahedra across the interface along with adequate lattice matches.