Deactivation of nitrogen donors in silicon carbide

Hexagonal SiC is either co-implanted with silicon (Si+), carbon (C+), or neon (Ne+) ions along with nitrogen (N+) ions or irradiated with electrons (e(-)) of 200 keV energy. During the subsequent annealing step at temperatures above 1450 degrees C a deactivation of N donors and a reduction of the compensation are observed in the case of the Si+/N+ co-implantation and e(-) irradiation. The N donor deactivation is investigated as a function of the concentration of the co-implanted species and the annealing temperature. The formation of energetically deep defects is analyzed with deep level transient spectroscopy. A detailed theoretical analysis based on the density functional theory is conducted; it takes into account the kinetic mechanisms for the formation of N interstitial clusters and (N-vacancy) complexes. In accordance with all the experimental results, this analysis distinctly indicates that the (N-C)(4)-V-Si complex, which is thermally stable at high temperatures and which has no level in the band gap of 4H-SiC, is responsible for the N donor deactivation.