" Soutenance de thèse de Abderazek TALBI le 11/12/2017 à 14h30 à l'amphi Boltzmann | Université d'Orléans

Université d'Orléans

Soutenance de thèse de Abderazek TALBI le 11/12/2017 à 14h30 à l'amphi Boltzmann

10/12/2017 (All day) - 14/12/2017 (All day)

Titre : Effect of ultra-short laser nanostructuring of material surfaces on the evolution of their thermoelectric properties.

Discipline : Physique

ECOLE DOCTORALE EMSTU

Résumé :

In this thesis work, we aimed to study the effect of surface nanostructuring of materials (mesoporous silicon and titanium oxide deposited in thin film) by ultra-short laser beams (picosecond and femtosecond) on the evolution of their thermoelectric properties. First, we focused on the study of various physical phenomena involved during the laser-matter interaction that yield to the formation of very different nanostructures in form of ripples, spikes, dots and others as function of the applied laser dose (fluence and number of pulses). The formation of these nanostructures has been studied in two regimes (stationary and dynamic). After optimizing the laser parameters leading to the formation of such nanostructures, the characterization of Seebeck coefficient and the electrical conductivity before and after the nanostructuring of these materials was carried out by using a new experimental setup (ZT-meter) designed and validated in GREMI laboratory. The results of measurements showed an important improvement of Seebeck coefficient and electrical conductivity after nanostructuring. This important improvement observed with the both materials leaded to a strong increase in the thermoelectric power factor (reaching roughly 50000%).