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 kinetics of structural phase formation and transformation 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 O⁺/cm² at different temperatures (160°C - 700°C). Subsequently, implanted samples were annealed up to 700°C for in situ studying during synthesis of buried oxide layers. Complementary, Transmission Electron Microscopy (TEM) and sputter Auger Electron Spectroscopy (AES) were employed to receive depth dependent information concerning the crystal structure and the elemental composition. The formation of different molybdenum oxides during oxygen implantation and post-implantation annealing process could be 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°C - 700°C preferably leads to the MoO₂ phase formation.