Structural characterization of crystalline Si-C-N films

摘要

High quality crystalline Si-C-N films on silicon substrate have been synthesized by biasassisted hot filament chemical vapor deposition (CVD) using a gas mixture of nitrogen and methane. Scanning electron microscopy images show that the Si-C-N clusters are composed of many columnar crystals with hexagonal facets. X-ray diffraction and transmission electron microscopy analyses confirm the formation of Si-C-N crystals with lattice parameters a-7.06A and c=2.72A. First principles calculations are performed for beta -Si_(3-n)C_nN_4 (n=0,1,2,3). The calculated results support the experimental structural characterization and provide further insight into the property of the system. With increasing amount of C substitution, the bulk modulus progressively increases to 4.44 Mbar, comparable to that of diamond (4.43 Mbar), and both a and c are reduced but the ratio c/a shows little variation.