Positron annihilation lifetime spectroscopy was used to investigate the evolution of the vacancy defects introduced into 12MeV H+ irradiated SiC as a function of temperature. Irradiation was performed at room temperature using a fluence of 4 x 1016/cm2 in 6H-SiC single crystals using a cyclotron. Heat treatment was performed under an Ar flux from 300 to 1050C. The positron lifetime was measured as a function of temperature at 15 to 600K. After irradiation, positrons detected negative ions and 2 types of vacancy defect: VSi monovacancies and VSi-VC divacancies. After annealing, the lifetime behavior as a function of the measurement temperature changed; indicating different annealing stages. An increase in the long-lifetime component was observed, while the corresponding intensity decreased. These changes were correlated to the migration of VSi and the clustering with VSi-VC to form a new vacancy defect. The lifetime of this new defect was determined and was equal to 235ps. It was suggested that it was related to VSi-VC-VSi.

Thermal Evolution of Vacancy Defects Induced in 12MeV H+ Irradiated 6H-SiC Single Crystals. X.Kerbiriou, M.F.Barthe, A.Gentils, P.Desgardin: Physica Status Solidi C, 2007, 4[10], 3650-3