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

Abstract

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 [ρ(T)], n- and p-type carrier concentration [n(T) and p(T)], and Hall mobility [μ(T)] of n-type Bi2Te3, p-type Sb2Te3, and p-type (Bi1−xSbx)2Te3 (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 (α), the values of α for Bi2Te3, Sb2Te3, and (Bi1−xSbx)2Te3 with x=0.73 and 0.77 are found to be −220, +110, +240, and +210 μV/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 (1019–1020) cm−3. The ρ(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)2Te3 (x=0.77) films where a maximum cooling of 2.6 °C was obtained with a low input current of 2.5 mA.

Impact of the Topological Surface State on the Thermoelectric Transport in Sb2Te3 Thin Films

“…However, in contrast to previous theoretical model calculations, 7,8 decreased values of S were found experimentally [9][10][11] for Bi 2 Te 3 and Sb 2 Te 3 thin films and were recently corroborated by both model 12,13 and ab initio calculations 4 of our groups.…”

“…[9][10][11] By means of ab initio electronic structure calculations based on density functional theory we discussed the thermoelectric properties of the p-type TI Sb 2 Te 3 for various film thicknesses and temperatures. The topologically protected surface-state leads to metallic conduction of the thin films even in the semiconducting regime.…”

Thermal annealing effect on structural and thermoelectric properties of hexagonal Bi2Te3 nanoplate thin films by drop-casting technique

“…The size of thin-film thermoelectric devices can be decreased further while increasing their Seebeck coefficient (by quantum size effect) and decreasing their thermal conductivity (by phonon scattering at the interfaces). [1][2][3][4] Among the thermoelectric materials, bismuth telluride (Bi 2 Te 3 ) is one of the most promising materials because it exhibits excellent thermoelectric performance at room temperature (RT) and has already been used as thermoelectric devices, including Peltier coolers [5][6][7] as well as power generators. [8][9][10] Bi 2 Te 3 has a rhombohedral crystal structure and a space group of D 5 3d ðR 3mÞ.…”

Review of 3D topological insulator thin‐film growth by molecular beam epitaxy and potential applications

“…In the past few decades, several other methods have also been used to grow thin films of V-VI compound semiconductors as thermoelectric materials, including MOCVD [34][35][36], electrochemical deposition [37,38], and co-evaporation [39]. Their growth mechanisms differ in their detailed processes.…”