Microstructure and initial growth characteristics of nanocrystalline silicon films fabricated by very high frequency plasma enhanced chemical vapor deposition with highly H2 dilution of SiH4

Abstract

Nanocrystalline silicon (nc-Si:H) film deposited on silicon oxide in a very high frequency plasma enhanced chemical vapor deposition with highly H2 dilution of SiH4 has been investigated by Raman spectroscopy and high resolution transmission electron microscopy. It is found that at early growth stage the initial amorphous incubation layer in nc-Si:H growth on silicon oxide can be almost eliminated and crystallites with diameter of about 6 to 10 nm are directly formed on the silicon oxide. Nearly parallel columnar structures with complex microstructure are found from cross-sectional transmission electron microscopy images of the film. It is considered that highly H2 dilution and higher excitation frequency are the main reason for eliminating the initial amorphous incubation layer in nc-Si:H growth on silicon oxide.