Photoluminescence of Radiation Defects in Cubic SiC: Localized Modes and Jahn-Teller Effect

Radiation defects were introduced into cubic SiC by 120-keV He-ion implantation, or by 1-MeV electron bombardment. Some of the defects persist after a 1600 ^∘{}C anneal. A low-temperature luminescence spectrum of one of the persistent defects reveals strong vibronic coupling, with localized and resonant modes. The spectrum has an unusual temperature dependence, with two abrupt changes below 13 ^∘{}K. The changes are attributed to the Jahn-Teller effect, and the distortion is accounted for by coupling with the 66.5-meV resonant mode. A possible model for the defect is the Watkins-Corbett impurity-vacancy model that was found to be appropriate for several persistent defects in Si.