The oxidation of nanocrystalline silicon powder (average crystallite size of 87 Å), prepared by laser-driven pyrolysis of SiH4, has been studied by X-ray diffraction and transmission electron microscopy. In a previous study the Si particles were shown to form perfect isolated near-spherical 'single crystals' that are stable up to 1073 K under high vacuum conditions. We have measured the size reduction of the Si nanoparticles in a flow of oxygen as a function of the degree of oxidation. The results are in agreement with model calculations for a shell-wise oxidation of silicon surface layers to amorphous silicon oxide. An oxidation to 50 vol.% implies a size reduction of 20% and tenfold improved visible photoluminescence intensity. Preliminary kinetic studies at 656 K in oxygen indicate a self-limiting type of oxidation, which is reached for an oxide layer thickness of ≈6.8 Å.
All Science Journal Classification (ASJC) codes
- Materials Chemistry
Vogel, W., Botti, S., Martelli, S., & Carlino, E. (1998). Shell-wise oxidation of nanocrystalline silicon observed by X-ray diffraction and TEM. New Journal of Chemistry, 22(7), 749 - 752. https://doi.org/10.1039/a709239c