Amorphous structures of silicon carbonitride formed by high-dose nitrogen ion implantation into silicon carbide

摘要

Short-range order in amorphous silicon carbonitride (a-SiC_xN_y) has been examined using transmission electron microscopy. Single crystals of 6H-SiC with [0001] orientation were implanted with 180 keV nitrogen ions at ambient temperature to a fluence of 5 x 10~(17) N~+/cm~2, followed by thermally annealing at 1500℃ for 30 min. A fully amorphous layer was formed at the topmost layer in the as-implanted sample. A part of the amorphous phase transformed into crystalline SiC after annealing. Radial distribution functions extracted via nano-beam electron diffraction patterns clearly showed that atomistic structures of the ion-beam-induced amorphous phase are different from those of the remaining amorphous phase in the annealed sample: a-SiC_xN_y possesses an intermediate bond length between Si-C and Si-N, while Si-N and Si-C bonds become more pronounced in the amorphous layer of the annealed specimen.