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

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. (c) 2007 American Institute of Physics.