X-ray photoelectron spectroscopy (XPS) has been used to determine the depth profile and chemical states of the implanted niobium in (0 1 1̄ 2) sapphire after annealing with a series of steps from 500 °C to 1100 °C in a reducing atmosphere. It is found that such an annealing procedure for the 380 keV niobium with a dose of 5 × 1016 ions/cm2 implanted into (0 1 1̄ 2) sapphire at room temperature causes Nb migration towards the surface and results in a two-peak feature distribution profile with the large peak at the surface. The implanted niobium in sapphire is in different local environments with different charge states after annealing. Higher charge states of Nb+5 and Nb+4 are distributed mainly in the near surface region due to oxidation under environment. The metallic state was caused by annealing in reducing atmosphere and was distributed mainly in the sub-surface region with a profile of two-peak feature. The other charge states such as Nb+2 and Nb+1 may be associated with the defects retained in sapphire and distributed to deeper distance. The concentration of each charge state of niobium with depth is also presented in this paper.
|Number of pages||9|
|Journal||Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms|
|Publication status||Published - 1998 Oct 1|
ASJC Scopus subject areas
- Nuclear and High Energy Physics