FABRICATION AND INVESTIGATION OF STRUCTURAL, OPTICAL AND DIELECTRICAL PROPERTIES OF BISMUTH TRISULFIDE (BI2S3) THIN FILM

Abstract

Bismuth trisulfide (Bi2S3) in thin films was prepared by spray pyrolysis method at temperature of 280°c. The films were of orthorhombic crystal structure, and direct optical gap of 1.61eV. Tangent of dielectric losses, AC conductivity, dielectric constant and electric modulus were investigated versus the frequency (5Hz-13MHz) and the temperature (293-333°K). The single electric relaxation time is of order of nano-second and DC conductivity from 0.29 to 3.22 (Ω.cm)-1, were indicated from electrical analysis. The observed behavior was described in term of a multi-hopping process. The dependence of ‘σAC’ and ‘S’ with temperature, were interpreted by the model (CBH). The density of the localized states N(Ef) is of order of 1020 cm-3.Ω-1, the maximum barrier height WM of order of 0.1eV, and the activation energy (Ea ≈0.12eV ) were calculated for these materials.