Formation and properties of stacking faults in nitrogen-doped 4H-SiC

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 nitrogen doping concentrations exceeding 2×1019 cm−3 after annealing at temperatures above 1100 °C. The double stacking faults form by glide of two partial dislocations in neighboring basal planes. Annealing experiments indicate that the partial dislocations originate from mechanically damaged crystal surfaces. The observed electrical and optical properties of 4H-SiC crystals containing double stacking faults can be well described by a quantum-well model. The conductivity asymmetry is 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 is suggested.