Influence of excitation frequency on the growth properties of nanocrystalline silicon films with high hydrogen dilution

Abstract

Nanocrystalline silicon films were prepared from SiH4 highly diluted with hydrogen by plasma enhanced chemical vapor deposition. The influence of excitation frequency on their growth properties was investigated. The cross-section transmisson electron microscopy images show that all the films grow with certain fastigiated structure in the crystalline region. However, the films deposited at 13.56 MHz undergo a transition from amorphous incubation layer to crystalline structure. In contrast, for the films deposited at a high excitation frequency (40.68 MHz), nanocrystalline silicon grains can directly grow on the amorphous substrates. Furthermore, the results of Raman spectra and Fourier transform infrared spectroscopy manifest that the nanocrystalline silicon films deposited at high excitation frequency (40.68 MHz) possess high crystalline fraction, low hydrogen content and small microstructure factor.