Growth and mechanism of one-dimensional Al ₂O ₃ nanostructures grown by chemical vapor deposition from an Al powder source

Alumina (Al ₂O ₃) nanostructures were grown in a horizontal Al ₂O ₃ tube furnace by chemical vapor deposition (CVD) using an aluminum (Al) powder source without catalysts at temperatures ranging from 1100 to 1400 °C and pressures ranging from 0.01 to 53.32 kPa. As the temperature and pressure were increased, the nanostructure size increased and in particular, increasing pressure resulted in various changes in morphology. Here we present a morphology diagram of the one-dimensional Al ₂O ₃ nanostructure growth to illustrate different growth features at various temperatures and pressures. Moreover, we suggest that the Al ₂O ₃ nanostructure deposition mechanism was affected by the liquid source droplet and film morphology as the temperature and pressure changed in the absence of catalysts.