Ion beam induced epitaxial crystallization of α-Al2O3 at room temperature

The structure of single crystal α-Al2O3 irradiated with 175 keV zirconium ions to fluences of 7.5 × 1015 and 1.5 × 1016 Zr/cm2 at room temperature, was investigated using Rutherford backscattering spectroscopy with ion channeling (RBS-C) and transmission electron microscopy (TEM). A buried amorphous layer was observed in samples irradiated at room temperature to a fluence of 1.5 × 1016 Zr+/cm2 (175 keV). The buried amorphous region is sandwiched between two highly-damaged crystalline regions. Nano-beam electron diffraction confirmed that both the near-surface damaged layer and the deeper damaged layer remained crystalline, but the buried amorphous region is lacking in long-range atomic order. Post irradiation using 55 keV oxygen ions at room temperature into pre-Zr-implanted samples produced ion beam-induced epitaxial crystallization (IBIEC) of the amorphous region adjacent to the near-surface damaged layer. Growth of the metastable polymorph γ-Al2O3 was observed at the amorphous/near surface damaged crystalline interface, as a result of this oxygen ion irradiation.