Thermoelectric properties of Cu and Sb co-doped Ga-Te based semiconductor with wide band gap

摘要

As a p-type semiconductor, Ga2Te5 has very low Seebeck coefficient and thermal conductivity. Cu, Sb co-doped Ga2Te5 based semiconductor was prepared by spark plasma sintering technique, and its band gap was measured decreasing from AEg//=1.77 eV represented by intrinsic state to 1.50 eV. X-ray analysis reveals the material crystallizes in the main phase Ga2Te5, but with Ga2Te3 and Sb2Te3 minor phases precipitated. The Seebeck coefficient increases from 150 (μV/K) to 275 (μV/K.) with temperature elevation, while the electrical conductivity decrease from 5.2xl0~1 (Ω~(-1), m~(-1)) to 2.4xl0~3 (Ω~(-1), m~(-1)), but still much higher than that of single crystal of Ga2Te5 reported at the corresponding temperature. The great improvement of electrical properties is closely related to the band gap narrowing, even though the impurity phases precipitated can influence the measured band gap value. The highest ZT value of 0.21 was obtained at 631 K for the Cu, Sb co-doped Ga2Te5 based semiconductor.