Positron annihilation spectroscopic studies of 6H silicon carbide

Positron lifetime measurements have been performed on p-type and n-type 6H-SiC with temperatures varying from 10 K to 290 K. The VCVSi divacancy is observed in both types of 6H-SiC where the VSi related defect is only found in the n-type material. Positron trapping into a defect with lifetime value close to the bulk was found to compete with positron trapping into VSi or VCVSi at temperatures lower than 80 K. The positron diffusion length of the 1400 C annealed n-type 6H-SiC has also been measured at different temperatures with the use of a positron beam. Positron diffusion was found to be limited by acoustic phonon scattering at T=150-300 K. However, at T=50-150 K, D+ follows T2.12±0.02 and the details of the physical process is not yet known. (orig.)