Effect of (Sm, In) Doping on the Electrical and Thermal Properties of Sb₂Te₃ Microstructures

Doped Sb₂Te₃ narrow-band-gap semiconductors have been attracting considerable attention for different electronic and thermoelectric applications. Trivalent samarium (Sm)- and indium (In)-doped Sb₂Te₃ microstructures have been synthesized by the economical solvothermal method. Powder X-ray diffraction (PXRD) was used to verify the synthesis of single-phase doped and undoped Sb₂Te₃ and doping of Sm and In within the crystal lattice of Sb₂Te₃. Further, the morphology, structure elucidation, and stability have been investigated systematically by scanning electron microscopy (SEM), Raman analysis, and thermogravimetric analysis (TGA). These analyses verified the successful synthesis of hexagonal undoped Sb₂Te₃ (AT) and (Sm, In)-doped Sb₂Te₃ (SAT, IAT) microstructures. Moreover, the comparison of dielectric parameters, including dielectric constant, dielectric loss, and tan loss of AT, SAT, and IAT, was done in detail. An increment in the electrical conductivities, both AC and DC, from 1.92 × 10^-4 to 4.9 × 10^-3 Ω^-1 m^-1 and a decrease in thermal conductivity (0.68-0.60 W m^-1 K^-1) were observed due to the doping by trivalent (Sm, In) dopants. According to our best knowledge, the synthesis and dielectric properties of (Sm, In)-doped and undoped Sb₂Te₃ in comparison with their electrical properties and thermal conductivity have not been reported earlier. This implies that appropriate doping with (Sm, In) in Sb₂Te₃ is promising to enhance the electronic and thermoelectric behavior.