Properties of dominant electron trap center in n-type SiC epilayers by means of deep level transient spectroscopy

摘要

Characterization of dominant electron trap in as-grown SiC epilayers has been carried out using deep level transient spectroscopy. Two electron traps E1 and Z_1 at E_c-0.21 and E_c-0.61 are observed, respectively; Z_1 being the dominant level. Line shape fitting, capture cross section, and insensitivity with doping concentration have revealed interesting features of Z_1 center. Spatial distribution discloses that the level is generated in the vicinity of epilayers/substrate interface and the rest of the overgrown layers is defect-free. Owing to the Si-rich growth conditions, the depth profile of Z_1 relates it to carbon vacancy. The alpha particle irradiation transforms Z_1 level into Z_1/Z_2 center involving silicon and carbon vacancies. Isochronal annealing study further strengthens the proposed origin of the debated level.