Optical properties of high-density amorphous carbon films grown by nanosecond and femtosecond pulsed laser ablation

Takashi Katsuno 1 Christian Godet 1 Jean-Christophe Orlianges 2, 3 A.-S. Loir 4 Florence Garrelie 4 Alain Catherinot 3
1 LPICM - Laboratoire de physique des interfaces et des couches minces [Palaiseau]
2 MINACOM
XLIM - XLIM
3 Axe 2 : procédés de traitements de surface
SPCTS - Science des Procédés Céramiques et de Traitements de Surface
4 LHC - Laboratoire Hubert Curien [Saint Etienne]
Abstract : High-density tetrahedral amorphous carbon (ta-C) films have been prepared by nanosecond (17 ns) and femtosecond (150 fs) pulsed laser deposition (PLD) using fluences and repetition rates compatible with fast and homogeneous growth over large areas. Their optical properties were measured by spectroscopic ellipsometry from 1.0 to 4.7 eV and analyzed using a multi-layer Tauc-Lorentz model. In spite of very different ablation mechanisms, both PLD techniques produce high density bulk layers as revealed by a refractive index (n at 2 eV) of 2.7±0.1 for both fs-PLD and ns-PLD. Films are covered by a few nm-thick sp2-rich top layer which is denser and thicker in femtosecond PLD as compared to nanosecond PLD. The respective roles of low and high energies in the kinetic energy distribution of the incident carbon species are discussed in terms of densification and sp3 →sp2 configurational relaxation predicted by the subplantation growth model. The significantly higher optical gap found in the ns-PLD films is attributed to the larger contribution of energetic species with kinetic energies Ec ≥ 200 eV, as revealed by time-of-flight optical studies.
Keywords : diamond-like carbon Pulsed laser deposition ellipsometry
Document type :
Journal articles
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https://hal-ujm.archives-ouvertes.fr/ujm-00170162
Contributor : Florence Garrelie <>
Submitted on : Thursday, September 6, 2007 - 3:26:09 PM
Last modification on : Tuesday, April 2, 2019 - 1:41:44 AM

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Takashi Katsuno, Christian Godet, Jean-Christophe Orlianges, A.-S. Loir, Florence Garrelie, et al.. Optical properties of high-density amorphous carbon films grown by nanosecond and femtosecond pulsed laser ablation. Applied physics. A, Materials science & processing, Springer Verlag, 2005, 81 (31), pp.471-476. ⟨ujm-00170162⟩

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