Positron annihilation spectroscopic studies of 6H silicon carbide

Abstract

Positron lifetime measurements have been performed on p-type and n-type 6H-SiC with temperatures varying from 10K to 290K. The V CV Si divacancy is observed in both types of 6H-SiC where the V Si 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 V Si or V CV Si at temperatures lower than 80K. 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=150-300K. However, at T=50-150K, D + follows T 2.12±0.02 and the details of the physical process is not yet known.