Formation and structural characterization of nanocrystalline Si/SiC multilayers grown by hot filament assisted chemical vapor deposition using CH₃SiH₃ gas jets

We report on the formation and the structural characterization of nanocrystalline Si/SiC (nc-Si/SiC) multilayers on Si(100) by hot filament assisted chemical vapor deposition using CH₃SiH₃ gas pulse jets. Si rich amorphous SiC (a-Si_{1 - x}C_x, x ~ 0.33) was initially grown at the substrate temperature (T_s) of 600 °C with heating a hot filament at ~ 2000 °C. The following crystalline SiC layers were grown at T_s = 850 °C without utilizing a hot filament. When the a-Si_{1 - x}C_x layer was ultrathin (< 2 nm) on Si(100), this a-Si_{1 - x}C_x layer was transformed to a single epitaxial SiC layer during the subsequent SiC growth process. The Si{111} faceted pits were formed at the SiC/Si(100) interface due to Si diffusion processes from the substrate. When the thickness of the initial a-Si_{1 - x}C_x layer was increased to ~ 5 nm, a double layer structure was formed in which this amorphous layer was changed to nc-Si and nc-SiC was grown on the top resulting in the considerable reduction of the {111} faceted pits. It was found that nc-SiC was formed by consuming the Si atoms uniformly diffused from the a-Si_{1 - x}C_x layer below and that Si nanocrystals were generated in the a-Si_{1 - x}C_x layers due to the annealing effect during further multilayer growths.