Diogo Machado

Structural and Morphological Changes In Ag:TiN Nanocomposite Films promoted by in-vacuum annealing

Thin films composed of titanium nitride doped with silver were deposited by DC reactive sputtering, with Ag contents varying between 0 and 50 at.%. The as-deposited samples were subjected to vacuum annealing treatments, with a range of temperatures varying from 200 to 500 °C, in order to study the morphological and structural changes that may occur. The as-deposited samples showed three main zones of basic characteristics, which differ both in terms of morphology and structural features. By increasing the annealing temperature, the thermodynamic stability is accelerated, giving rise to (i) a uniform dispersion of silver particles at 200 °C; (ii) the start of segregation at 300 °C; (iii) at 400 °C the coalescence of the segregated Ag particles takes place and finally (iv) at 500 °C the formation of large Ag clusters is evident, particularly within the zone that comprises the samples with higher Ag content. In addition to corroborate the presence of free Ag in Ag:TiN thin films, the increasing annealing temperature promotes the improvement of the coatings crystallinity, as well as Ag grain growth.

Ag:TiN nanocomposite thin films for bioelectrodes: The effect of annealing treatments on the electrical and mechanical behavior

Magnetron sputtered Ag:TiN thin films, with Ag contents ranging from 0 to ∼50 at. %, were subjected to a set of annealing treatments at four different temperatures (from 200 to 500 °C), aiming at studying the effect of Ag addition on their morphological and structural features, as well as on their electrical and mechanical properties. The increase of the annealing temperature revealed that significant morphological modifications were induced, mainly in the samples with higher Ag contents (represented by the sample with an Ag content of 36.3 at. %), which revealed extensive Ag segregation to the surface. The increase of the annealing temperature up to 500 °C, besides confirming the presence of metallic Ag in the coatings, also resulted in some major structural changes, promoting an increase in the coatings crystallinity and an extensive Ag grain growth phenomenon. Nevertheless, the resistivity values of all annealed samples were found to be only slightly higher when comparing to the as-deposited ones, whi...