Nanostructured Thermoelectric PbTe Thin Films with Ag Addition Deposited by Femtosecond Pulsed Laser Ablation

Pulsed laser deposition operated by an ultra-short laser beam was used to grow in a vacuum and at room temperature natively nanostructured thin films of lead telluride (PbTe) for thermoelectric applications. Different percentages of silver (Ag), from 0.5 to 20% of nominal concentration, were added to PbTe deposited on polished technical alumina substrates using a multi-target system. The surface morphology and chemical composition were analyzed by Scanning Electron Microscope and X-ray Photoelectron Spectroscopy, whereas the structural characteristics were investigated by X-ray Diffraction. Electrical resistivity as a function of the sample temperature was measured by the four-point probe method by highlighting a typical semiconducting behavior, apart from the sample with the maximum Ag concentration acting as a degenerate semiconductor, whereas the Seebeck coefficient measurements indicate n-type doping for all the samples. The power factor values (up to 14.9 mu W cm(-1) K-2 at 540 K for the nominal 10% Ag concentration sample) are competitive for low-power applications on flexible substrates, also presuming the achievement of a large reduction in the thermal conductivity thanks to the native nanostructuring.

Automated summary

Pulsed laser deposition with ultra-short laser beam was used to grow nanostructured thin films of lead telluride (PbTe) for thermoelectric applications. Silver (Ag) was added to PbTe at different percentages, and the surface morphology, chemical composition, and structural characteristics were analyzed. Electrical resistivity measurements showed semiconductor behavior for most samples, while Seebeck coefficient measurements indicated n-type doping. The power factor values were competitive and suitable for low-power applications on flexible substrates.