Synthesis and Characterization of Amorphous Si₂N₂O

Amorphous silicon oxynitride powder was synthesized by nitridation of high‐purity silica in ammonia at 1120°C. The resulting material was X‐ray amorphous, and its chemical characteristics were determined by X‐ray photoelectron spectroscopy (XPS) and ²⁹Si nuclear magnetic resonance (NMR). The XPS analysis showed a shift to lower binding energies for the Si₂p peak with increasing nitrogen content. Upon initial nitridation, the full width at half maximum (FWHM) of the Si₂p peak increased, but decreased again at higher nitrogen contents, thus showing the formation of a silicon oxynitride phase with a single or small range of composition. The ²⁹Si NMR analysis showed the formation of (amorphous) Si₃N₄ (Si–N₄) and possibly two oxynitride phases (Si–N₃O, Si–N₂O₂). It is concluded that while XPS, FT‐IR, and nitrogen analysis may show the formation of an homogeneous, amorphous silicon oxynitride (Si₂N₂O) phase, the formation of phase–pure, amorphous Si₂N₂O is extremely difficult via this route.