Characteristics and Optical Properties of Bi2Te2.45Se0.55 Thin Film

Abstract

Thermally evaporated Bi2Te2.45Se0.55 thin films were examined for structural alterations and electrical conductivity. Crystallite size, micro-strain, and dislocations were all calculated using the XRD data. By using transmission electron microscopy, the morphology of thin films was investigated (TEM). The study was performed within a temperature range of (300 – 500) K. The electrical energy gap and the conductivity of the as-deposited and annealed (373, 473K) Bi2Te2.45Se0.55 films were measured. The obtained values are (0.27, 0.26, 0.24 eV) and 3.6×103, 3.7×103 and 4.1×103 ohm-1.cm-1 respectively. Hall coefficient, the mean free time, the diffusion coefficient of holes, and the diffusion length, charge carrier's concentration, charge carriers' scattering mechanism, and Hall mobility were also examined. The obtained values of the charge carrier's concentration are 2.12×1017 -2.73×1017 cm-3. The direct and indirect allowed energy gap decreased with increasing annealing temperature. The obtained values of indirect band gap and direct band gap ranges from 0.27- 0.24 eV and 0.375- 0.379 eV, respectively.