High quality microcrystalline silicon-carbide films prepared by photo-CVD method using ethylene gas as a carbon source

Hydrogenated boron-doped microcrystalline silicon-carbide (p-mu c-SiC:H) films were grown by a photo chemical vapor deposition (photo-CVD) method from silane (SiH4), hydrogen (H-2), diborane (B2H6), and ethylene (C2H4) gases. Since the photo-CVD is a mild process (similar to 10mW/cm(2)), we can avoid the ion damage of the film, which is inevitable during the deposition of mu c-SiC:H employing conventional PECVD technique. A dark conductivity as high as 5 x 10(-1) S/cm, together with an optical bandgap of 2 eV, was obtained by the C2H4 addition, which is the first approach in photo-CVD systems. From the Raman and FTIR spectra, it is clear that our p-mu c-SiC:H films are made up of crystalline silicon grains embedded in amorphous silicon-carbide tissue. We investigate the role of the hydrogen dilution and ethylene addition on the electrical, optical, and structural properties of p-mu c-SiC:H films.