Low-temperature (120 ℃) growth of nanocrystalline silicon films prepared by plasma enhanced chemical vapor deposition from SiCl_4/H_2 gases: Microstructure characterization

摘要

Hydrogenated nanocrystalline silicon (nc-Si:H) films were prepared using diluted tetrachlorosilane (SiCl_4) with various hydrogen flow rates (Hf) by plasma enhanced chemical vapor deposition (PECVD) at a constant substrate temperature (Ts) as low as 120℃. Raman spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), infrared spectra (IR) and spectroscopic ellip-sometry (SE) were employed to investigate the microstructure and hydrogen bonding of the nc-Si:H films. Our results showed that the microstructure and hydrogen content of the films could be effectively tailored by the hydrogen flow rates, and a distinct transition from amorphous to nanocrystalline phase was observed with an increase of Hf. At an optimal preparation condition, a deposition rate was as high as 3.7 nm/min and the crystallinity reached up to 64.1 %. In addition, the effect of hydrogen on the low-temperature growth of nc-Si:H film was proposed in relation to the surface reaction of radicals and the hydrogen diffusion in the surface growing region.