Influence of magnetic impurities on thermoelectric capabilities of Bi_2Te_3, Sb_2Te_3, and Bi_2Se_3

摘要

Temperature dependencies of the Seebeck coefficient, electrical conductivity, heat conductivity and the dimensionless thermoelectric figure of merit ZT of p-Bi_2Te_3, n-Bi_2Se_3 and Sb_2Te_3 doped by Fe or Cr have been investigated in the temperature interval 7 ＜ T ＜ 300 K. At T＝4.2 K the Shubnikov-de Haas and Hall effects have been measured. By increasing the Fe content, the hole concentration decreases in p-Bi_(2-x)Fe_xTe_3, while the electron concentration increases in n-Bi_(2-x)Fe_xSe_3. The hole concentration decreases in Sb_(2-x)Cr_xTe_3 with Cr doping. This demonstrates that Fe or Cr act as donors. The Seebeck coefficient increases in p-Bi_(2-x)Fe_xTe_3 and Sb_(2-x)Cr_xTe_3 with increasing Fe or Cr content, while it decreases in n-Bi_(2-x)Fe_xSe_3.