A comparative study on the electronic and optical properties of Sb-=SUB=-2-=/SUB=-Se-=SUB=-3-=/SUB=- thin film

Abstract

The thin film of Sb 2 Se 3 was deposited by thermal evaporation method and the film was annealed in N 2 flow in a three zone furnace at a temperature of 290• C for 30 min. The structural properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy, respectively. It is seen that the as-deposited film is amorphous and the annealed film is polycrystalline in nature. The surface of Sb 2 Se 3 film is oxidized with a thickness of 1.15 nm investigated by X-ray photolecetron spectroscopy (XPS) measurement. Spectroscopic ellipsometry (SE) and UV-vis spectroscopy measurements were carried out to study the optical properties of Sb 2 Se 3 film. In addition, the first principles calculations were applied to study the electronic and optical properties of Sb 2 Se 3 . From the theoretical calculation it is seen that Sb 2 Se 3 is intrinsically an indirect band gap semiconductor. Importantly, the experimental band gap is in good agreement with the theoretical band gap. Furthermore, the experimental values of n, k, ε 1 , and ε 2 are much closer to the theoretical results. However, the obtained large dielectric constants and refractive index values suggest that exciton binding energy in Sb 2 Se 3 should be relatively small and an antireflective coating is recommended to enhance the light absorption of Sb 2 Se 3 for thin film solar cells application.