Reduction in thermal conductivity and electrical resistivity of indium and tellurium co-doped bismuth selenide thermoelectric system

Polycrystalline samples of (Bi_1-xIn_x)₂Se_2.7Te_0.3 (x = 0.00, 0.02, and 0.04) were prepared by the solid-state reaction technique. X-ray diffraction pattern confirms that the polycrystalline samples have a hexagonal structure with spacegroup R3 - m. The surface morphologic study reveals the existence of porous behavior in the studied samples due to the volatilization of Selenium. Energy dispersive X-ray analysis validates the expected and observed elemental composition of the samples. Electrical resistivity has shown metallic behavior. Hall effect and Seebeck coefficient measurements indicate the p-type and n-type conduction for the pristine sample Bi₂Se₃ and the (Bi_1-xIn_x)₂Se_2.7Te_0.3 samples, respectively. The thermal conductivity and electrical resistivity were found to reduce by 7.5 and 9 times, respectively, for (Bi_0.96In_0.04)₂Se_2.7Te_0.3 compared to the pristine sample Bi₂Se₃.