Vacancy defects in p-type 6H-SiC created by low-energy electron irradiation

The intrinsic defects in p-type 6H-SiC:Al generated by electron irradiation at 300 keV, which is close to the threshold of the silicon atom displacement, have been studied by electron paramagnetic resonance spectroscopy. We observed two dominant irradiation-induced paramagnetic defects: (i) a silicon-vacancy-related spin S = 3/2 defect with a zero-field splitting of D = 68.7 X 10(-4) cm(-1), which is tentatively attributed to a Si Frenkel pair aligned parallel to the c axis and (ii) a carbon-vacancy-related spin S = 1/2 defect already previously attributed to V-C(+). A slight increase of the electron energy to 350 keV creates in addition a lower-symmetry S = 3/2 spectrum equally attributed to Si Frenkel pairs with the interstitial being located at six equivalent off-axis sites. High-energy irradiation (2 MeV) creates only isolated Si vacancies with no zero-field splitting.