The effect of tin doping on the band structure and optical properties of polycrystalline antimony selenide.

In this study, we investigated the effect of Sn-doping on the antimony selenide (Sb 2 Se 3) polycrystalline material to alter its optical properties and electronic band structure. Sb 2 Se 3 polycrystals were isothermally annealed at 350 °C, 400 °C, 450 °C, and 500 °C, in the presence of tin diselenide (SnSe 2) in degassed quartz ampoules to introduce Tin (Sn) into the material. X-ray diffraction (XRD), Raman scattering, and energy-dispersive X-ray spectroscopy measurements confirmed the single phase of the Sb 2 Se 3 samples. Successful doping of the surface of the Sb 2 Se 3 polycrystals with Sn was confirmed by X-ray photoelectron spectroscopy for the samples annealed at 400 °C, 450 °C, and 500 °C in the presence of SnSe 2. An ultraviolet photoelectron spectroscopy (UPS) study revealed a decrease in the work function (Ф) of the Sb 2 Se 3 polycrystals from 4.34 eV to 3.14 eV due to Sn doping implemented at 500 °C. Moreover, a small shift of the Fermi level towards the valence band maximum (VBM) by 30 meV resulted from Sn-doping at 500 °C as was detected by UPS, indicating a slightly enhanced p-type behaviour of the surface region of the Sb 2 Se 3 polycrystals. Ultraviolet–visible spectroscopy (UV–Vis) confirmed that Sn doping did not change the bandgap energy of Sb 2 Se 3 polycrystals, being 1.25 eV at room temperature (RT) for the undoped as well as Sn-doped material. [ABSTRACT FROM AUTHOR]