Transport properties of V-VI semiconducting thermoelectric BiSbTe alloy thin films and their application to micromodule Peltier devices

Thin semiconducting thermoelectric films with narrow energy band gaps are considered to be very promising for future microdevice applications (sensors and generators). The polycrystalline BiSbTe alloys (V-VI semiconductors) are examples. In this report, the detailed temperature dependence of electrical resistivity [rho (T)], n- and p-type carrier concentration [n(T) and p(T)], and Hall mobility [mu (T)] of n-type Bi2Te3, p-type Sb2Te3, and p-type (Bi1-xSbx)(2)Te-3 (x=0.73 and 0.77) alloy films prepared by metalorganic chemical vapor deposition are presented in the range of 100-500 K. From the room temperature measurement of the Seebeck coefficient (alpha), the values of alpha for Bi2Te3, Sb2Te3, and (Bi1-xSbx)(2)Te-3 with x=0.73 and 0.77 are found to be -220, +110, +240, and +210 muV/K, respectively, which are optimal in these types of film materials. The carrier concentration of these films at 300 K is found to be around (10(19)-10(20)) cm(-3). The rho (T) data show an exponential increase with increasing temperature irrespective of the carrier types. For the temperature dependence of the Hall mobility, the lattice contribution is found to be predominant for all the films. Also, we have fabricated a simple micromodule Peltier device (MMP) using the n-type Bi2Te3 and the p-type (Bi1-xSbx)(2)Te-3 (x=0.77) films where a maximum cooling of 2.6 degreesC was obtained with a low input current of 2.5 mA. (C) 2001 American Institute of Physics.