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|Title:||Nanomechanical properties of multilayered amorphous carbon structures||Authors:||Patsalas, Panos
Kelires, Pantelis C.
|Keywords:||Carbon;Silicon;Chemical structure;Elasticity;Monte Carlo method;Thermal analysis||Issue Date:||2002||Publisher:||APS American Physical Society||Source:||Physical Review B - Condensed Matter and Materials Physics,2002, Volume 65, Issue 20, Pages 2052031-20520314||Abstract:||A possible route toward reducing the intrinsic compressive stress in as-grown amorphous carbon films on Si substrates, with a high fraction of tetrahedral bonding, is by forming multilayered a-C structures composed of layers dense and rich in sp3 sites alternated by layers rich in sp2 geometries, a type of an amorphous superlattice. We present here a combined theoretical and experimental effort to investigate the stability, stress, and elastic properties of this type of a-C material. Our theoretical approach is based on Monte Carlo simulations within an empirical potential scheme, while the experimental part consists of spectroscopic ellipsometry, x-ray reflectivity, stress, and nanoindentation measurements in films prepared by magnetron sputtering. Our central result is that the average stress in the multilayered structures is nearly eliminated through layer-by-layer stress compensation, yet the fraction of sp3 sites in the dense regions remains high, sustained by the overwhelmingly compressive local stresses. The sp3-rich layers are stable both against a moderate increase of the width of the low-density layers, as well as under thermal annealing. The elastic moduli of the multilayered films are comparable with those of single-layer films. This, in conjuction with their low stress, makes them suitable for mechanical purposes.||URI:||http://ktisis.cut.ac.cy/handle/10488/7537||ISSN:||1098-0121||DOI:||10.1103/PhysRevB.65.205203||Rights:||© 2002 The American Physical Society.||Type:||Article|
|Appears in Collections:||Άρθρα/Articles|
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