Synthesis and X-ray photoelectron spectroscopy (XPS) and thermoelectric studies of ternary Bi2(Te_(0.5)8e_(0.5))3 mixed-metai chalcogenide thin films by the arrested precipitation technique

摘要

Arrested precipitation technique (APT) has been successfully employed for the deposition of Bi2(Te_(0.5)Se_(0.5))3 thin films. Analytical grade bismuth nitrate complexes with triethanolamine (TEA), sodium tellurosulfite, and sodium selenosul-fite were used as precursor materials. The film was obtained at 55 ± 0.5 °C in an aqueous alkaline medium (pH = 10.5 ± 0.2). As-deposited film was characterized by chemical compositional, optical, and electrical analyses. The optical absorption spectrum for the sample was recorded in the wavelength region 400-900 nm. It shows a high coefficient of absorption (α = 10~5 cm~(-1)) with an allowed direct type of transition. X-ray diffraction (XRD) study of the film shows a nanocrystalline and rhombohedral structure. From scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive X-ray analysis (EDAX) studies, the deposited film shows uniform morphology and good stoichiometry. X-ray photoelectron spectroscopy (XPS) was used to study the binding energy and surface oxidation of the material. Electrical conduction study shows that material is an n-type semiconductor and shows good thermoelectric figure of merit.