Ion Beam Induced Darkening in Tetrahedral Amorphous Carbon Thin Films
M. Sandulov a, M. Berova a, T. Tsvetkovaa and J. Zuk b
aInstitute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria
bInstitute of Physics, Maria Curie-Skłodowska University, pl. M. Curie-Skłodowskiej 1, 20-031 Lublin, Poland
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The samples of thin film (d ≈40 nm) tetrahedral amorphous carbon (ta-C), deposited by the filtered cathodic vacuum arc have been implanted with N+ at a fluence of 3×1014 cm-2 and ion energy E=20 keV. The induced structural modification of the implanted material results in a considerable change of its optical properties, best manifested by a significant shift of the optical absorption edge to lower photon energies as obtained from optical transmission measurements. This shift is accompanied by a considerable increase of the absorption coefficient (photodarkening effect) in the measured wavelength range (350÷2500 nm). These effects could be attributed to both the additional defect introduction and the increased graphitization, as confirmed by the X-ray photoelectron spectroscopy measurements. The optical contrast thus obtained (between implanted and unimplanted film materials) could be made use of in the area of high-density optical data storage using the focused ion beams.

DOI: 10.12693/APhysPolA.128.953
PACS numbers: 81.05.U-, 68.55.Ln, 42.70.Ln