Crystallinity of silicon films grown on carbon fibers by very high frequency plasma enhanced chemical vapor deposition

In this work, silicon films were deposited on carbon fibers using very high frequency (60 MHz) plasma enhanced chemical vapor deposition (VHF-PECVD) to form Si/carbon fiber hybrid structures for the applications to the flexible solar cell. The effect of deposition conditions of VHF-PECVD such as hydrogen flow rate and R.F. power on the microstructure of Si films was investigated with Raman spectroscopy, X-ray diffraction, field emission scanning electron microscopy, and high resolution transmission electron microscopy. The crystallinity of Si films on carbon fibers showed strong dependence on the hydrogen flow rate and was changed from amorphous structure to partially crystallized structure with increasing hydrogen flow rate. Increasing R.F. power enhanced the crystallinity for amorphous Si films while deteriorated the crystallinity for partially crystallized Si films on carbon fibers. And it was observed that the crystallinity of silicon films on carbon fibers was increased drastically by thermal annealing above 500 °C.