Mechanical and field emission properties of CGed Si(C,N) films synthesized by PECVD from HMDS precursor

Compositionally graded (CGed) Si(C,N) films were prepared by Ar/H2/N2 plasma enhanced chemical vapor deposition from liquid injected hexamethyldisiloxane precursor. The films were characterized by scanning/transmission electron microscopy (SEM/TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Monolithic crystalline SiC and amorphous SiNx films were produced from Ar/H2 and Ar/H2/N2 thermal plasma, respectively. The CGed SiC–SiNx film was obtained by changing N2 flow rate from 2 L/min to zero in Ar/H2/N2 during the deposition process, and it was composed of an uppermost crystalline SiC layer, a thin intermediate layer containing nanocomposite c-SiC/a-SiNx and an innermost layer of amorphous SiNx. The CGed SiNx–SiC film, in which SiNx acts as a top layer with a SiC layer underneath, was fabricated by an inverse change of the plasma gas supply from initial Ar/H2 to Ar/H2/N2. Microhardness increase and promising field emission properties were obtained from these CGed films in comparison with monolithic SiC and SiNx films.