Crystallization in SiO₂-metal oxide alloys

HfO₂-SiO₂ and La₂O₃-SiO₂ amorphous alloys were prepared, and their crystallization behavior was studied. The results suggest that higher permittivities can be achieved in the La-containing system without devitrification. The crystallization mechanisms between systems are distinctly different, yet observations are consistent with bulk material. Hf-containing materials tend toward phase separation, while La-containing materials tend toward silicate formation. For Hf-containing films, negligible thickness or time dependence was observed. In La-containing films, rapid thermal anneals could improve crystallization resistance, and thickness effects related to interface reactions were observed. These behaviors are discussed in the context of phase diagrams and metastable immiscibility.