The low temperature donor-acceptor pair photoluminescence spectra of n
-type 6H-SiC has been investigated, both theoretically and experimenta
lly. The excitation intensity dependence of the maximum position and w
idth of the no-phonon line has been observed down to the lowest limit
of experimental excitation intensity. We show that the majority impuri
ty (donor) concentration can be obtained from the line-shape of the ex
perimental spectra. The value of the donor concentration found in this
way is in good agreement with the result of independent electrical me
asurements. (C) 1997 Elsevier Science S.A.