Nitrogen deactivation by implantation-induced defects in 4H-SiC epitaxial layers

Ion implantation causes free charge carrier reduction due to damage in the crystalline structure. Here, nitrogen-doped 4H silicon carbide (n type) epi taxial layers have been investigated using low ion doses in order to resolv e the initial stage of the charge carrier reduction. It was found that the reduction of free carriers per ion-induced vacancy increases with increasin g nitrogen content. Nitrogen is suggested to be deactivated through reactio n with migrating point defects, and silicon vacancies or alternatively inte rstitials are proposed as the most likely candidates. (C) 2001 American Ins titute of Physics.