Excitation and recombination dynamics of vacancy-related spin centers in   silicon carbide
  We generate silicon vacancy related defects in high-quality epitaxial silicon carbide layers by means of electron irradiation. By controlling the irradiation fluence, the defect concentration is varied over several orders of magnitude. We establish the excitation profile for optical pumping of these defects and evaluate the optimum excitation wavelength of 770 nm. We also measure the photoluminescence dynamics at room temperature and find a monoexponential decay with a characteristic lifetime of 6.1 ns. The integrated photoluminescence intensity depends linear on the excitation power density up to 20 kW/cm$^2$, indicating a relatively small absorption cross section of these defects. 
T. C. Hain, F. Fuchs, V. A. Soltamov, P. G. Baranov, G. V. Astakhov,   T. Hertel, V. Dyakonov
cond-mat.mtrl-sci