Synthesis and X-ray photoelectron spectroscopy (XPS) and thermoelectric studies of ternary Bi2(Te0.5Se0.5)3 mixed-metal chalcogenide thin films by the arrested precipitation technique

Abstract

Arrested precipitation technique (APT) has been successfully employed for the deposition of Bi2(Te0.5Se0.5)3 thin films. Analytical grade bismuth nitrate complexes with triethanolamine (TEA), sodium tellurosulfite, and sodium selenosulfite 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 = 105 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.