Enhancement of electrical transport through the anisotropic nanostructure performance of heavily Yb-doped PbSe0.2Te0.8 thin films

Solid-state microwave-assisted plasma technique was used to synthesize high-purity Pb1−xYbxSe0.2Te0.8 from initial components to obtain polycrystalline ingots with large grains. Pb1−xYbxSe0.2Te0.8 thin films were then deposited onto glass substrates using thermal evaporation in vacuum. The films have the polycrystalline rock salt-type (NaCl) structure. The crystal lattice parameters for the powders and thin films obtained from X-ray diffraction (XRD) patterns showed that the values of the lattice parameters increased with increasing Yb content. The field emission scanning electron microscopy images reveal that the Pb1−xYbxSe0.2Te0.8 thin films have uniform crystal grain sizes and dense nanostructures. The electrical transport properties of the thin films were measured in the temperature range of 298 K–523 K. The Seebeck coefficient of the films increased with x when x was in the range of 0.015–0.045, whereas it decreased for x between the range of 0.06 and 0.105. The carrier concentration was 4.3 × 1017 cm−3 for x = 0.015, and the maximum value was 6.34 × 1017 cm−3 at x = 0.075.