Enhancement of ZT in Bi0.5Sb1.5Te3 Thin Film through Lattice Orientation Management
Journal
Nanomaterials
Journal Volume
14
Journal Issue
9
Start Page
747
ISSN
2079-4991
Date Issued
2024-04-25
Author(s)
Wei-Han Tsai
Cheng-Lung Chen
Ranganayakulu K. Vankayala
Ying-Hsiang Lo
Wen-Pin Hsieh
Te-Hsien Wang
Yang-Yuan Chen
Abstract
Thermoelectric power can convert heat and electricity directly and reversibly. Low-dimensional thermoelectric materials, particularly thin films, have been considered a breakthrough for separating electronic and thermal transport relationships. In this study, a series of Bi0.5Sb1.5Te3 thin films with thicknesses of 0.125, 0.25, 0.5, and 1 μm have been fabricated by RF sputtering for the study of thickness effects on thermoelectric properties. We demonstrated that microstructure (texture) changes highly correlate with the growth thickness in the films, and equilibrium annealing significantly improves the thermoelectric performance, resulting in a remarkable enhancement in the thermoelectric performance. Consequently, the 0.5 μm thin films achieve an exceptional power factor of 18.1 μWcm−1K−2 at 400 K. Furthermore, we utilize a novel method that involves exfoliating a nanosized film and cutting with a focused ion beam, enabling precise in-plane thermal conductivity measurements through the 3ω method. We obtain the in-plane thermal conductivity as low as 0.3 Wm−1K−1, leading to a maximum ZT of 1.86, nearing room temperature. Our results provide significant insights into advanced thin-film thermoelectric design and fabrication, boosting high-performance systems.
Subjects
annealing
energy efficiency
sustainable manufacturing
thermoelectric
thin films
Publisher
MDPI AG
Type
journal article