Control of the figure of merit by the anti-site defect in thermoelectric materials (Bi,Sb)2Te3

Basic physical properties of the thermoelectric materials of p-type (Bi,Sb)(2)Te-3 have been measured. The temperature TZ-peak, at which the figure of merit Z takes a maximum, the resistivity and the Seebeck coefficient show the linear Hall coefficient dependences. These behaviors are strongly related to the anti-site defect between the Bi (or Sb) and the Te site and the TZ-peak systematically decreases with the decrease of the anti-site defect which corresponds to the decrease of the number of hole carriers. It is proposed that the figure of merit could be controlled by the anti-site defect. A possibility of the application of the thermoelectric materials at low temperature is also proposed.