Electrically active defects in n-type 6H-SiC diode structures have been studied by deep level transient spectroscopy (DLTS) and high-resolution Laplace DLTS. It is shown that the commonly observed broadened DLTS peak previously ascribed to two traps referenced as E1/E2 has three components with activation energies for electron emission of 0.39, 0.43, and 0.44 eV. Further, defects associated with these emission signals have similar electronic structure, each possessing two energy levels with negative-U ordering in the upper half of the 6H-SiC gap. It is argued that the defects are related to a carbon vacancy at three non-equivalent lattice sites in 6H-SiC. © 2013 American Institute of Physics. ; cited By (since 1996)1