Deposition of n-Type Bi₂Te₃ Thin Films on Polyimide by Using RF Magnetron Co-Sputtering Method

Abstract

Bi2Te3 thermoelectric thin films were deposited on the flexible polyimide substrates by RF magnetron co-sputtering of a Bi and a Te targets. The influence of the substrate temperature and RF power on the microstructure, chemical composition, and the thermoelectric properties of the sputtered films was investigated by using scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and in-plane resistivity/Seebeck coefficient measurement. It was shown that the thermoelectric properties of the films depend sensitively on the Bi/Te chemical composition ratio and the substrate temperature, and the layered structure was clearly observed from the cross section of the (00L)-oriented, nearly stoichiometric Bi2Te3 films when the substrate temperature is higher than 250 °C. As-deposited Bi2Te3 films deposited at 300 °C show the highest power factor of 0.97 mW/K(2)m and the Seebeck coefficient of -193 μV/K at 32 °C, which also have (00L) preferred orientation and the layered structure. The durability of the Bi2Te3 films on polyimide against repeated bending was also tested by monitoring the film resistance, and it was concluded that the Bi2Te3 films are applicable reliably on the curved surfaces with the radius of curvature larger than 5 mm.

High-Performance μ-Thermoelectric Device Based on Bi2Te3/Sb2Te3 p–n Junctions

“…Furthermore, with the increase of σ, the PF also increases. In conclusion, our PF values are comparable to or even greater than those obtained in the literature for films with >1 μm thickness. − ,, …”

“…In conclusion, our PF values are comparable to or even greater than those obtained in the literature for films with >1 μm thickness. [23][24][25]31,32 Performance of μ-TEG. A TEG is a solid-state device that converts temperature differences directly into electrical energy, through the Seebeck effect.…”

Flexible Thermoelectric Paper and Its Thermoelectric Generator from Bacterial Cellulose/Ag2Se Nanocomposites

“…The electrical barrier from the presence of the voids in the BC/Ag 2 Se structure could suppress both n and μ from the strong electrical scattering, resulting in the reduced electrical conductivity. This is why the BC/Ag 2 Se paper exhibits relatively low electrical conductivity compared to other reports for flexible TE thin films. ,,, …”

“…In the last decade, many efforts have been dedicated to the research on flexible TE materials and composites, such as TE thin films on flexible substrates, − conductive polymers, and polymer/ conductive filler composites. − Thin films of TE materials that possess high TE efficiency have been deposited on flexible substrates. For example, the Bi 2 Te 3 thin films were deposited on polyimide and carbon nanotube (CNT) substrates, and exhibited excellent flexibility with a very large TE power factor (PF).…”

Study of the Annealing Effects of Sputtered Bi2Te3Thin Films with Full Thermoelectric Figure of Merit Characterization

“…Various deposition techniques have been investigated for the deposition of Bi 2 Te 3 thin films, including chemical vapor deposition (CVD), [ 21–24 ] ECD, [ 25,26 ] and PVD. [ 27–31 ] Due to their high TE efficiency compared with ECD materials, sputtered Bi 2 Te 3 films are often used for the fabrication of micro‐TE devices. [ 19,20 ] However, the as‐deposited thin films typically have a predominantly amorphous state with poor crystallinity and therefore low ZT .…”