AVS 50th International Symposium
    Thin Films Friday Sessions
       Session TF-FrM

Paper TF-FrM9
Synthesis of Super-Elastic Fullerene-Like Carbon Nitride Coatings by Unbalanced Reactive Magnetron Sputtering

Friday, November 7, 2003, 11:00 am, Room 329

Session: Mechanical Properties of Thin Films
Presenter: J. Neidhardt, Linköping University, Sweden
Authors: J. Neidhardt, Linköping University, Sweden
Zs. Czigány, Hungarian Academy of Sciences
L. Hultman, Linköping University, Sweden
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Carbon nitride (CN@sub x@) is an emerging material for wear-resistant coatings. Out of several characteristic structures, the so-called fullerene-like (FL) compounds are the most promising. The FL structure leads to extraordinary mechanical properties such as an extreme elasticity combined with high fracture toughness as assessed by nano indentation. Yet, FL-CN@sub x@ shows a low-to-moderate resistance to penetration. Hence, deformation energy is predominantly stored elastically and released after unload giving it the resilient character. The key for understanding its resilient character lies in a unique microstructure of bent, cross-linked and frequently intersecting nitrogen-containing graphite sheets, denoted "fullerene-like". This presentation elaborates on the growth mechanisms of FL CN@sub x@ synthesised by unbalanced reactive magnetron sputtering of graphite in a nitrogen-containing atmosphere. Preformed C@sub x@N@sub y@ (x, y < 2) species originating from the target were assigned a crucial role for the fullerene-like structure evolution. In fact, the conducted plasma analysis revealed that the majority of the film forming flux comprises multi atomic nitrogen-containing species, which are partly sputtered and also thermally emitted from the self-modified target surface. The arrival of C@sub x@N@sub y@ molecules besides carbon atoms at the substrate surface adds much complexity to the growth mechanisms. C@sub x@N@sub y@ species may act as growth templates whereas an oriented incorporation along the edges makes them more stable towards preferential chemical desorption and therefore the formation of extended and curved sheet-like structures is promoted. Also the role and extent of temperature dependent chemical desorption (sputtering) process for the FL structure evolution was investigated in order to identify the type of species incorporated.