Structure studies of synthetic diamond thin films by x-ray diffraction

The depth profile of the structure of synthetic diamond thin films prepared by the d.c. arc discharge plasma chemical vapour deposition (CVD) method has been investigated by sample-tilting X-ray diffraction. The results show that, at first, a layer of carbide is deposited which saturates the substrate surface. For a single-crystal silicon (c-Si) substrate, the compound is silicon carbide (SiC); for a molybdenum wafer substrate, the compound is molybdenum carbide (Mo₂C). A diamond film grows on the carbide layer. The orientation of the crystal grains with depth in the polycrystalline diamond thin films is irregular. The main contaminant in diamond thin films prepared by the d.c. arc discharge plasma CVD method is tungsten carbide (WC).