A high density of double stacking faults consisting of six Si-C bilayers in cubic stacking sequence could be observed in 4H-SiC crystals with N doping concentrations exceeding 2 x 1019/cm3 after annealing at temperatures above 1100C. The double stacking faults formed by glide of 2 partial dislocations in neighboring basal planes. Annealing experiments indicated that the partial dislocations originate from mechanically damaged crystal surfaces. The observed electrical and optical properties of 4H-SiC crystals containing double stacking faults could be well described by a quantum-well model. The conductivity asymmetry was caused by the build-up of potential barriers in c-direction. For the luminescence an indirect radiative recombination of excitons accompanied by momentum-conserving phonons and additionally replicated by the LO(Γ) phonon was suggested.

Formation and Properties of Stacking Faults in Nitrogen-Doped 4H-SiC. K.Irmscher, M.Albrecht, M.Rossberg, H.J.Rost, D.Siche, G.Wagner: Physica B, 2006, 376-377, 338-41