1Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 2School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074
Abstract：Bi$_{2}$Te$_{3}$ thin films and GeTe/B$_{2}$Te$_{3}$ superlattices of different thicknesses are prepared on the silicon dioxide substrates by magnetron sputtering technique and thermally annealed at 573 K for 30 min. Thermoelectric (TE) measurements indicate that optimal thickness and thickness ratio improve the TE performance of Bi$_{2}$Te$_{3}$ thin films and GeTe/B$_{2}$Te$_{3}$ superlattices, respectively. High TE performances with figure-of-merit ($ZT$) values as high as 1.32 and 1.56 are achieved at 443 K for 30 nm and 50 nm Bi$_{2}$Te$_{3}$ thin films, respectively. These $ZT$ values are higher than those of p-type Bi$_{2}$Te$_{3}$ alloys as reported. Relatively high $ZT$ of the GeTe/B$_{2}$Te$_{3}$ superlattices at 300–380 K were 0.62–0.76. The achieved high $ZT$ value may be attributed to the unique nano- and micro-structures of the films, which increase phonon scattering and reduce thermal conductivity. The results indicate that Bi$_{2}$Te$_{3}$-based thin films can serve as high-performance materials for applications in TE devices.
2017, Vol. 34 
