Vacancies and deep levels in electron-irradiated 6H SiC epilayers studied by positron annihilation and deep level transient spectroscopy

The annealing behavior of defects in n-type 6H SiC epilayers irradiated wit h 2 MeV electrons have been studied using positron annihilation and deep le vel transient spectroscopy. Vacancy-type defects are annealed at 500-700 de greesC and 1200-1400 degreesC. From the analysis of Doppler broadening spec tra (core electron momentum distribution), the latter annealing process is attributed to the disappearance of complexes related to silicon vacancies a nd not to nearest neighbor divacancies. Among the observed deep levels, the E-1/E-2 levels show similar annealing behavior to that of positron annihil ation centers above 1000 degreesC. It is thus proposed that the E-1/E-2 lev els originate from complexes containing silicon vacancies. (C) 2001 America n Institute of Physics.