Fs-pulsed laser deposition of PbTe and PbTe/Ag thermoelectric thin films

Abstract

For the first time, thermoelectric thin films were fabricated by femtosecond pulsed laser deposition (fs-PLD) that represents a challenging technological solution for this application since it provides a correct film stoichiometry compared to the starting target, capability of native nanostructuring and a high deposition rate. In particular, this paper shows a preliminary work on PbTe and PbTe/Ag thin films deposited at different substrate temperatures by fs-PLD from a microcrystalline PbTe target. Structural, morphological and compositional characterizations of the deposited films were performed to demonstrate the formation of films composed by crystalline nanograins (about 35 nm size) and characterized by a correct stoichiometry. A remarkable deposition rate of 1.5 nm/s was evaluated. The electrical conductivity and the Seebeck coefficient (thermopower) were measured as a function of operating temperature to derive the thermoelectric power factor that was found to be less than a factor 2 with respect to the bulk materials. Finally, a discussion about the influence of compositional and structural properties of the deposited films on the related thermoelectric performances was presented.

Extracellular production of tellurium nanoparticles by the photosynthetic bacterium Rhodobacter capsulatus

“…4). The peak-fitting routine applied to the Te 3d 5/2 signal showed the presence of 2 peaks at BE 573.1 eV and 576.4 eV, assigned to metallic and oxidized state of tellurium [30]. As the XPS analysis invests mainly few nanometers of the nanoparticles superficial layers, the great abundance of organic material suggests the presence of an external coating.…”

Preliminary characterization of ST2G: Solar thermionic-thermoelectric generator for concentrating systems

“…In the next experiments, this aspect will be carefully taken into account. In parallel, thermoelectric nanostructured materials are under development to fabricate higher-operating-temperature higher-efficiency TE modules 12,13 .…”

Material optimization via combinatorial deposition and analysis for thermoelectric thin films

“…The biggest advantage of PLD for combinatorial studies over other thin film deposition techniques, such as chemical vapor deposition or molecular beam epitaxy, is the ability to transfer complex stoichiometries from a target material to the film [19]. PLD also provides unique nanostructuring in thin films, including texturing and dimensional reduction, which can further enhance the TE performance [20]. The electrical resistivity of Ca 3 Co 4 O 9 is anisotropic with respect to the crystallographic orientation [21].…”

“…Highly textured Ca 3 Co 4 O 9 thin films have been successfully deposited on a wide variety of substrates yielding power factors which are improved with respect to cold pressed and sintered bulk materials primarily due to the reduction of electrical resistivity [22,23]. Several groups are working on transitioning these thin films directly into thermoelectric generators [1,20,24]; however, this enhancement via texturing can also be realized in bulk Ca 3 Co 4 O 9 via hot pressing, spark plasma sintering [25], or tape casting [26][27][28].…”