Optical properties of sprayed Bi2S3 nanocrystalline thin film

Bismuth Sulfide (Bi2S3) thin film was prepared by spray pyrolysis on glass substrate at 270 degrees C, by using bismuth chloride (BiCl3) and Thiourea (CS (NH2)(2)). The optical constants and thickness were extracted using the pattern search optimization technique. The optical constants confirm that the Bi2S3 film has a direct gap of 1.56 eV. The dispersion of refractive index in Bi2S3 was analyzed using the concept of the single oscillator model. The dielectric constants represented by the lattice dielectric, the dispersion parameters E-0 and E-d, and the rth moments, M-1 and M-3 were determined. It is interesting to note that Bi2S3 appears to fall into the covalent class. The values ratio of the carrier concentration to effective masse and plasma frequency were also evaluated.