In situ characterization of phase formation during high-energy oxygen ion implantation in molybdenum

A special designed high-temperature vacuum chamber for in situ X-ray diffraction (XRD) measurements was used to study structural phase formation and transformation kinetics in molybdenum during oxygen ion implantation and post-annealing treatment. Oxygen ions with an energy of 1.5 MeV were implanted in polycrystalline molybdenum up to a fluence of 3 × 1018/cm2 at different temperatures (160-700 °C). Subsequently, implanted samples were annealed up to 700 °C for in situ study during synthesis of buried oxide layers. Complementary, transmission electron microscopy (TEM) and sputter Auger electron spectroscopy (AES) were employed to obtain depth-dependent information concerning both the crystal structure and its elemental composition. The formation of different molybdenum oxides during oxygen implantation and post-implantation annealing process was observed by in situ X-ray analysis. The XRD spectra of samples implanted at 160 °C show that MoO3 and/or Mo4O11 precipitates have been formed, whereas implantation in the temperature range 300-700 °C preferably leads to the MoO2 phase formation.