Effective mass donors in silicon carbide - a study with electron nuclear double resonance

With electron nuclear double resonance the superhyperfine interactions of n umerous Si-29 and C-13 lattice neighbours of N-14 donors in 3C and 4H-SiC h ave been measured. It was attempted to explain them using the effective mas s theory (EMT). The interactions of N donors on cubic sites in 3C-SiC can b e well explained with EMT assuming N to be on C sites, but not on Si sites. N in 3C-SiC represents probably the only true EMT donor, since for shallow donors in Si EMT is not sufficient as shown previously. The interactions o f N on the hexagonal sites in 4H-SiC are still reasonably well explained, w hile the EMT approach fails to explain N on the quasi-cubic sites. Comparis on between 3C-SiC and 4H-SiC shows that the "central cell corrections" due to the chemical nature of N introduced into EMT previously for silicon is v ery small. The major contribution comes from inter-valley interactions. (C) 1999 Elsevier Science B.V. All rights reserved.