Understanding the role of carbon in active trap centre formation in porous alumina


Understanding the role of carbon in active trap centre formation in porous alumina

Bhowmick, S.; Pal, S.; Das, D.; Khan, S. A.; Gupta, M.; Barman, S. R.; Kanjilal, D.; Hübner, R.; Kanjilal, A.

In recent days, carbon doped alumina (Al2O3:C) are gaining immense interest as a potential radiation dosimetric material due to very high thermoluminescence (TL) sensitivity [1]. Despite of some theoretical predictions [2, 3] as well as experimental results, exact role of carbon in forming active trap centres in alumina matrix is still not conclusive, and thus it requires further investigation. Here we report a detailed study of porous alumina in a systematic way by various complementary techniques, such as HAADF-STEM, EDS mapping, X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS) before and after carbon doping. For that, ion beam implantation technique has been employed due to controlled incorporation of carbon in selective areas of Al2O3. Further, the anodized alumina with a porous structure is expected to play a crucial role due to high surface-to-volume ratio. Amorphous porous alumina has been synthesized electrochemically [4] where the porous structure have been confirmed by SEM and TEM. The amorphous nature is also consistent with the GIXRD results. The corresponding elemental mapping suggests the carbon penetration depth in the amorphous Al2O3 matrix. Detailed XAS and depth dependent XPS studies reveal possible role of carbon atoms in Al2O3 as active trap centres, and so the TL response. The observed results are in good agreement with the recent theoretical works, and therefore will be helpful for further improvement of dosimetric sensing.
1. G. O. Sawakuchi et al. J. Appl. Phys. 104 (2008) 124903
2. H. D. Tailor et al. J. Vac. Sci. & Technol. A 33 (2015) 01A120
3. L. Ao et al. J. Appl. Phys. 122 (2017) 025702
4. H. Masuda et al. Science 268 (1995) 1466

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