Theoretical and experimental analyses to determine the effects of crystal orientation and grain size on the thermoelectric properties of oblique deposited bismuth telluride thin films

Abstract The best known thermoelectric material for near room temperature heat-to-electricity conversion is bismuth telluride. Amongst the possible fabrication techniques, electrodeposition has attracted attention due to its simplicity and low cost. However, the measurement of the thermoelectric properties of electrodeposited films is challenging because of the conducting seed layer underneath the film. Here, we develop a method to directly measure the thermoelectric properties of electrodeposited bismuth telluride thin films, grown on indium tin oxide. Using this technique, the temperature dependent thermoelectric properties (Seebeck coefficient and electrical conductivity) of electrodeposited thin films have been measured down to 100 K. A parallel resistor model is employed to discern the signal of the film from the signal of the seed layer and the data are carefully analysed and contextualized with literature. Our analysis demonstrates that the thermoelectric properties of electrodeposited films can be accurately evaluated without inflicting any damage to the films.

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Improvement of Thermoelectric Properties of Bismuth Telluride Thin Films using Rapid Thermal Processing

Korean Journal of Materials Research ◽

10.3740/mrsk.2006.16.5.292 ◽

2006 ◽

Vol 16 (5) ◽

pp. 292-296 ◽

Cited By ~ 1

Author(s):

Dong-Ho Kim ◽

Gun-Hwan Lee

Keyword(s):

Thin Films ◽

Thermoelectric Properties ◽

Bismuth Telluride ◽

Thermal Processing ◽

Rapid Thermal Processing

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Effect of Grain Size and Film Thickness on the Thermoelectric Properties of Flexible Sb2Te3 Thin Films

Advances in Materials Science and Engineering ◽

10.1155/2019/6954918 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7 ◽

Cited By ~ 12

Author(s):

Pornsiri Wanarattikan ◽

Piya Jitthammapirom ◽

Rachsak Sakdanuphab ◽

Aparporn Sakulkalavek

Keyword(s):

Thin Films ◽

Thermal Conductivity ◽

Electrical Conductivity ◽

Grain Size ◽

Film Thickness ◽

Seebeck Coefficient ◽

Thermoelectric Properties ◽

Flexible Substrate ◽

Rf Magnetron Sputtering ◽

Mean Free Path

In this work, stoichiometric Sb2Te3 thin films with various thicknesses were deposited on a flexible substrate using RF magnetron sputtering. The grain size and thickness effects on the thermoelectric properties, such as the Seebeck coefficient (S), electrical conductivity (σ), power factor (PF), and thermal conductivity (k), were investigated. The results show that the grain size was directly related to film thickness. As the film thickness increased, the grain size also increased. The Seebeck coefficient and electrical conductivity corresponded to the grain size of the films. The mean free path of carriers increases as the grain size increases, resulting in a decrease in the Seebeck coefficient and increase in electrical conductivity. Electrical conductivity strongly affects the temperature dependence of PF which results in the highest value of 7.5 × 10−4 W/m·K2 at 250°C for film thickness thicker than 1 µm. In the thermal conductivity mechanism, film thickness affects the dominance of phonons or carriers. For film thicknesses less than 1 µm, the behaviour of the phonons is dominant, while both are dominant for film thicknesses greater than 1 µm. Control of the grain size and film thickness is thus critical for controlling the performance of Sb2Te3 thin films.

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