Effect of Doped Aluminium into Bismuth Telluride on the Structural and Optical Properties by Thermal Evaporation

In this research, the structural, morphological, and optical properties of Bi2Te3 at different thicknesses (100, 200, 300 nm) and different concentrations of Al (2%, 4% and 6%) at a thickness of 100 nm for thin films. were studied that revealed the formation of the hexagonal Bi2Te3 structure for undoped and Al-doped films, XRD studies showed that the average size of the grains increased with increasing Al content from 2% to 6%, the lattice constant of the doped films was greater than the value in the international test card, the density of dislocations decreased as the Al content increased, and We also observed that the number of crystals per unit area increased with increasing thickness at (300 nm) was (0.1714 × 1010 m-3), and decreased with increasing Al content for the films at (6%) was (0.051 × 1010 m-3). EDX spectroscopy spectra demonstrated the incorporation of Al into the doped films. The optical reflectance (R%) of pure Bi2Te3 at different thicknesses, Bi2Te3/Al films, were recorded in the range of 350-840 nm. The R% were profoundly affected by Al doping. The optical bandgap decreased from 2.12 to 1.99 eV as the Al content increased from 2% to 6%. The observed optical properties of Bi2Te3/Al thin films may allow for the selection of materials with specific applications in mind, such as optical design.