Thermoelectric transport properties of n-doped and p-doped Bi0.91Sb0.09 alloy thin films

In order to understand the doping behavior of extremely narrow band gap materials and to optimize their characteristics for use in a thermoelectric module, we performed n- and p- type doping experiments on semiconducting Bi0.91Sb0.09 alloy thin films using the group VI(IV) element Te(Sn) as donor (acceptor). Thermoelectric power (TEP), electrical resistivity, and Hall effect were studied in the range of temperatures 5-300 K. Increased Sn doping causes the TEP to change sign (from negative to positive) and the maximum in the TEP can be controlled with the dopant concentration. Increased Te doping causes the TEP to decrease. The maximum Te- oped electron concentration was about 5x10(20) cm(-3) and the highest Sn-doped hole concentration was about 1x10(21) cm(-3). Highly Sn- and Te-doped samples show degenerate behavior in the electrical resistivity, TEP and Hall measurements. (C) 1999 American Institute of Physics. [S0021-8979(99)02707-3].