Positron lifetime spectroscopic studies of as-grown 6H-silicon carbide

Abstract

Positron lifetime spectroscopy has been employed to study the as-grown n-type 1.2 × 1018 cm-3 N-doped and p-type 1.8 × 1018 cm-3 Al-doped 6H-silicon carbide in the temperature range 10 K-300 K. For the p-type material, a positron trapping site, which has a lifetime of 225 ± 11 ps, was found and is attributed to positron annihilating from the VSi VC divacancy-related defect having a neutral charge. For the case of the n-type material, a positron trapping centre having a lifetime of 200±9 ps, attributed to a VSi-related defect, and a shallow trap were observed. The shallow trap, having binding energy of 18 meV was attributed to Rydberg-like states resulting from positron binding with a negative ion.