6533b7d1fe1ef96bd125c8eb

RESEARCH PRODUCT

Couches minces d'oxynitrure de titane : la réactivité comme moyen original de caractérisation physico - chimique

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Titanium oxinitride thin films, TiNxOy, were elaborated on Si(100) by the MOCVD (Metal Organic Chemical Vapor Deposition) method, using titanium isopropoxide Ti(OCH(CH3)2)4 and ammonia NH3 as precursors. By varying the growth temperature, it is possible to modify the N/O ratio and change the conductivity of the films.The target of this work was to determine the composition and the structure of these TiNxOy thin films in order to understand the electrical properties. However, this study was difficult because classical characterization techniques (SEM, XRD, Raman, XPS...) were unable to describe the whole TiNxOy system. Indeed, only a structure which is isomorphic to TiN (NaCl structure) was detected in the samples elaborated at high temperature ( T > 550 °C) and quantitative analysis revealed relatively high oxygen content in all the samples. This study was broadened to TiN films in order to understand the importance of oxygen in this structure.Original characterization methods, based on the fact that it is possible to link the structure of a material to its reactivity, were carried out in order to complete previous characterizations. In particular, the study of the reactivity of thin films towards ion bombardment or thermal treatments allowed to determine and quantify the different phases which are present in TiNxOy thin films. For low synthesis temperatures (T < 700 °C) they are composed of a conducting Ti(N,O) phase and an insulating TiO2 one. A percolation model allowing the understanding of the conductivity variations as a function of the films synthesis temperature was proposed thanks to these characterization methods.