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摘要
The present work investigates the radiation damage, amorphization and structural modifications that are produced by ion-solid interactions in TiO2 crystals during 200 keV Cobalt ion implantation. RBS/C and GIXRD have been utilized to evaluate the damage in the host lattice as a function of ion fluence. Multiple scattering formalism has been applied to extract the depth dependent damage distributions in TiO2(110). The results have been compared with the MC simulations performed using SRIM-2013. RBS/C results delineate a buried amorphous layer at a low fluence. Surprisingly, ion induced dynamic activation produces a recovery in this damage at higher fluences. This improvement interestingly occurs only in deep regions (60-300 nm) where a systematic lowering in damage with fluence is observed. Formation of Co-Ti-O phases and generation of stress in TiO2 lattice can also be responsible for this improvement in deep regions. In contrast, surface region (0-60 nm) indicates a gradual increase in damage with fluence. Such a switch in the damage behavior creates a cross point in damage profiles at 60 nm. Surface region is a sink of vacancies whereas deep layers are interstitial rich. However, these regions are far separated from each other resulting in an intermediate (100-150 nm) region with a significant dip (valley) in damage which can be characterized by enhanced recombination of point defects. The damage profiles thus indicate a very complex behavior. MC simulations, however, present very different results. They depict a damage profile that extends to a depth of only 150 nm, which is only about half of the damage-width observed here via RBS/C. Moreover, MC simulations do not indicate presence of any valley like structure in the damage profile. The complex nature of damage distribution observed here via RBS/C may be related to the high ionic nature of the chemical bonds in the TiO2 lattice.
- 出版日期2017-11-1
