Optical and electrical properties of a-Si1-xCx:H and uc-Si1-xCx:H films prepared by using methane and xylene source

Hydrogenated amorphous silicon carbide (a-Si1-xCx:H) films were fabricated in the plasma-enhanced chemical vapor deposition system by using silane (SiH4) and two kind of carbon sources, methane (CH4) and xylene (C8H10), respectively. The optical band gap of methane-made a-Si1- xCx:H was varied from 1.9 eV to 2.6 eV while that of xylene-made a-Si1-xCx:H could be extended to 3.5 eV. Fourier transform infrared spectra demonstrated the existence of aromatic ring in xylene-made a-Si1-xCx:H, which is much different from the carbon configuration of methane-made a-Si1-xCx:H. Visible light emission at room temperature was observed from xylene-made a-Si1-xCx:H films. The photoluminescence peak shifted from 630 nm (1.97 eV) to 450 nm (2.75 eV) when the optical band gap of samples increased from 2.3 eV to 3.5 eV. KrF pulse laser with wavelength of 248 nm was used to crystallize these two kinds of films at room temperature. For both samples the conductivities can reach 10-5S/cm and are enhanced by over four orders of magnitude.