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 displaceme nt, have been studied by electron paramagnetic resonance spectroscopy. We o bserved two dominant irradiation-induced paramagnetic defects: (i) a silico n-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 al igned 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 e lectron energy to 350 keV creates in addition a lower-symmetry S = 3/2 spec trum equally attributed to Si Frenkel pairs with the interstitial being loc ated at six equivalent off-axis sites. High-energy irradiation (2 MeV) crea tes only isolated Si vacancies with no zero-field splitting.