Formation of core-shell structured silicon nanoparticles during pulsed laser ablation

Abstract

We performed pulsed laser ablation of Si target in nitrogen background gas and found that core-shell structured nanoparticles can be prepared without postsurface treatment. The predominant ejected species from the target at free expansion region is Si, and N related species appears at the point blast region. The core-shell structure and plume expansion dynamics suggest that nuclei of the Si nanodroplets are formed in early stage followed by growth of nanodroplets and nitraidation at the surfaces region of the nanodroplets. Formation of core shell structure is a result of nonequilibrium high energy pulsed ejection of Si species.