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Nanostructured and disordered carbon thin films are widely investigated nowadays due their numerous technological potentialities in domains such as hardcoatings, optoelectronics and new electrode materials for example. Such a wide range of targeted applications is the result of the very rich set of properties recognised for this kind of materials: high chemical (and electrochemical) stability, high electrical conductivity (when optimised), hardness, resistance to corrosion, high potential window in aqueous media, field emission, and a great variety of structures and compositions accessible from the control of the C sp2/sp3 ratio that itself depends on the incorporation modes of heteroatoms (nitrogen and hydrogen mainly).
In this contribution, various amorphous carbon nitride (a-CNx) films were deposited on silicon and mica substrates using the RF magnetron sputtering technique with a graphite target. A nitrogen percentage varying in the 1%-30% range was imposed in these films by controlling the argon/nitrogen plasma composition. Morphological and electrical investigations of these films were carried out as a function of the nitrogen percentage in the film using Atomic Force Microscopy (AFM) either in the contact mode or in the current-sensing mode (CS-AFM).
By this means, an obvious influence of the nitrogen percentage in the plasma on the roughness (RMS) of these materials was established. In parallel, the mapping of their surface conductivity was carried out using the current-sensing mode of AFM (CS-AFM). It was thus observed that the surface conductivity of such films can be correlated first with the nitrogen percentage in the plasma as it varies from poor to very high as the N % varies from 30 % to 1 %. It can also be correlated with their surface topography as great variations of surface conductivities were measured between "grains" and "grain boundaries". Conductivity curves were also obtained and thoroughly exploited to identify further the mapped surface conductivities.
On the basis of the numerous observations collected in this work, correlations between composition and surface properties such as topography, conductivity and reactivity will be suggested and discussed.
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