CHARACTERIZATION OF OXIDE LAYERS INDUCED BY OXYGEN-ION IMPLANTATION INTO TI, V, CR, ZR, NB, MO, HF, TA AND W

The mechanism of oxide formation induced by ion implantation with and without mass-analyzed oxygen ions into nine refractory metals of groups IVa, Va, and VIa in the periodic table was investigated by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectrometry (RBS). O2+ ions were implanted at an energy of 75 keV per atom with dose ranging from 1 x 10(17) to 2 x 10(18) ions CM-2 at room temperature using the RIKEN low current ion implanter. The SIT-100 direct ion implanter was used for oxygen ion implantation without mass separation at an acceleration voltage of 80 kV at room temperature. Profiles of implanted oxygen were measured by XPS and RBS and the oxides induced by implantation were identified by XRD. XRD patterns showed almost the same process of oxide formation for both mass-analyzed and non-mass-analyzed implantation. In the case of titanium, however, an effect of energy deposition during the formation of oxides was found by comparing oxides induced by ion implantation with and without mass separation. The formation process was approximately classified into three groups in relation to the groups and periods of the periodic table of elements. The stoichiometric ratio of oxides induced by implantation with high doses is discussed based on data obtained by XRD, XPS and RBS. Finally, the aging behavior of oxides kept in an evacuated desiccator for about 1 year is discussed.