Electric and thermoelectric properties of electrodeposited bismuth telluride (Bi2Te3) films

Abstract

We investigated the relationships among the deposition potential, the electric properties, and the thermoelectric properties of Bi2Te3 films electrodeposited from a solution containing 1.00mM TeO2 and 0.86mM Bi-EDTA complex. From the results of the Hall-effect measurements, the films formed at >−0.27V vs Ag∕AgCl were Te-rich n-Bi2Te3, and the carrier concentration increased with more negative deposition potential. The films formed at <−0.35V were Bi-rich p-Bi2Te3, and the carrier concentration showed a constant value. A depth profile showed that all the electrodeposited films were composed of two layers, and that an n-type layer containing a large excess of Te existed near the substrate surface. From the Seebeck coefficient measurements, the electrical type of all the films was n type, and the maximum Seebeck coefficient (−70±10μVK−1) was observed for the film deposited at −0.20V. The electrical type obtained by the Seebeck coefficient measurements was completely different from the electrical type determined by the Hall-effect measurements. This difference could be explained by the p-n junction formation near the substrate surface.

A novel route to nanostructured bismuth telluride films by electrodeposition

“…For all other solutions Te rich compositions were obtained, for a stoichiometry close to Bi 2 Te 8 . Variation of the deposition potential over the range -0.375 V to -0.05 V vs SCE was found to have no significant influence on the composition of the electrodeposited films which is consistent with literature reports [17,18]. Grazing incidence (GI) X-ray diffraction (XRD) data as shown in Figure 2 reveals a series of well-defined and sharp diffraction peaks that can be indexed as belonging to rhombohedral Bi 2 Te 3 with a space group of R3m according to the standard ICDD card (PDF-2/release 2012 RDB).…”

Electrodeposition and Thermoelectric Characteristics of Bi2Te3 and Sb2Te3 Films for Thermopile Sensor Applications

“…7,8,10 While various processing techniques such as evaporation, metalorganic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and electrodeposition can be used for thermoelectric thin-film fabrication, electrodeposition is attractive because it is a rapid and inexpensive process. [7][8][9][10][11][12][13][14] In this study, n-type bismuth telluride (Bi-Te) and p-type antimony telluride (Sb-Te) films were electrodeposited with varying bath compositions and electrodeposition potentials, respectively, and their thermoelectric properties were evaluated for thermopile sensor applications. A thermopile sensor was processed on a glass substrate by electrodeposition and photolithography of the n-type Bi-Te and the p-type Sb-Te films, and its thermal sensing properties were characterized by applying controlled temperature differences by using a thin-film heater formed on the thermopiles.…”

Thermoelectric Thin Film Device of Cross-Plane Configuration Processed by Electrodeposition and Flip-Chip Bonding

“…The BiTe films exhibited the negative Seebeck coefficients, which was coincident with the fact that the Te-rich Bi 2 Te 3 is n-type and the Bi-rich Bi 2 Te 3 is p-type. 21) The Seebeck coefficients of the BiTe films were in the range of ¹51.8 to ¹59.8 µV/K, which were much lower than the ¹200 µV/K reported for bulk Bi 2 Te 3 , resulting the quite low power factors, compared to those of the Bi 2 Te 3 bulk materials. 22) Such low Seebeck coefficients of the BiTe films could be attributed to the high carrier concentration, not listed here, due to the heavy doping of the films inherently resulted from an electrodeposition process.…”