Deactivation of nitrogen donors in silicon carbide

Schmid, F.*; Reshanov, S. A.*; Weber, H. B.*; Pensl, G.*; Bockstedte, M.*; Mattausch, A.*; Pankratov, O.*; Oshima, Takeshi; Ito, Hisayoshi

Hexagonal SiC is co-implanted with silicon Si, carbon C, or neon Ne ions along with nitrogen N ions. Also hexagonal SiC irradiated with electrons e of 200 keV energy. During the subsequent annealing step at temperatures above 1450 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. Using Hall measurement, the N donor deactivation is studied 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)-V complex, which is thermally stable at high temperatures, is responsible for the N donor deactivation.