Deposition and optical properties of amorphous hydrogenated SixCy layers

Thin films of amorphous hydrogenated silicon-carbon alloys of different compositions were deposited onto silicon and glass substrates by electron cyclotron resonance plasma enhanced chemical vapour deposition using silane and methane as gas precursors. Growth rate dependences were studied for different [CH][CH4 + SiH4] gas flow ratios. The films were characterized by optical transmission spectroscopy in the 200–2600 nm wavelength range, Fourier transform IR transmission spectroscopy and Raman spectroscopy. Optical parameters (refractive indices, absorption and extinction coefficients and optical band gap) were extracted from transmission spectra. The refractive index (at wavelength 1300 nm) was found to be between 3.2 and 2.0, and the optical band gap was in the range 1.75 to 2.3 eV, depending on experimental conditions.