Enhancement in thermoelectric properties of flexible antimony telluride films deposited by direct current magnetron sputtering

Name: Prasopporn Junlabhut

LCSH: Thermoelectric materials

Abstract: Thermoelectric technology has been utilized for energy harvesting in the Microwatt power range. P-type Sb₂Te₃ is a narrow band gap semiconductor with a Rhombohedral layered crystal structure and is a well-known thermoelectric material for near room temperature applications. To date, the preparation of these chalcogenide materials in film form is required to fabricate on a flexible substrate. For energy harvesting applications, the maximum output power is proportional to the film thickness. This thesis. P-type Sb₂Te₃ films with different thicknesses were deposited on polyimide substrates via heat treatment-assisted DC magnetron sputtering. The annealing temperature and annealing time were optimized to enhance thermoelectric properties.The correlations between the thickness variance and the structure, dislocation density, surface morphology, thermoelectric properties and output power are investigated. As a result, the film thickness and the heat treatment process during growth are related to the diffusion of deposited atoms on the substrate surface, leading to imperfection defects inside the films. The structure revealed that the preferred orientation plane along the (001) plane was changed to the (015) plane as the thickness dimension of the film increased, indicating that the atomic interactions between atoms and substrate can obstruct nucleation in the vertical direction. This texture change had a significant impact on electrical transportation. The residual stress typically accumulates as the thick layer increases, which is related to the diffusion of deposited atoms on the substrate surface and to the appearance of microstructure and morphology. The thermal energy of the thick dimension is not enough cause diffusion and agglomeration. The resultant surface morphology showed small compact grains as the film thickness increased. All imperfections inside the films are affected by the thermoelectric properties. The maximum power output factor of 2.73 mW/mK2 for a film thickness of 9.0 pm was obtained following annealing at 350°c for 30 min. Experimental characterization showed that increasing the film thickness to 9.0 pm at a deposition time of 60 min can produce an output power of 0.032 µW at a temperature difference of 58 K

King Mongkut's Institute of Technology Ladkrabang. Central Library

Address: BANGKOK

Email: Lifelong@kmitl.ac.th

Name: Aparporn Sakulkalavek

Role: Thesis Advisor

Email : aparporn.sa@kmitl.ac.th

Created: 2021

Modified: 2566-05-25

Issued: 2023-05-25

วิทยานิพนธ์/Thesis

application/pdf

eng

DegreeName: Doctor of philosophy

Descipline: Applied Physics

Grantor: King Mongkut's Institute of Technology Ladkrabang

Level: Doctoral Degree

©copyrights King Mongkut's Institute of Technology Ladkrabang

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