Thermoelectric properties of DC-sputtered filled skutterudite thin film

• Published in: Journal of applied physics 2015-03, Vol.117 (12), p.125304
• Main Authors: Fu, Gaosheng, Zuo, Lei, Chen, Jie, Lu, Ming, Yu, Liangyao
• Format: Article
• Language: English
• Subjects: Applied physics; Carrier density; Crystal structure; Crystallinity; Degree of crystallinity; Electrical resistivity; Electron mobility; Energy dispersive X ray spectroscopy; Figure of merit; Hall effect; Heat conductivity; Heat transfer; Heat treatment; High temperature effects; Magnetron sputtering; Phase composition; Photovoltaic cells; Scanning electron microscopy; Seebeck effect; Thermal conductivity; Thermoelectricity; Thin films; X-ray diffraction
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4916238

The Yb filled CoSb3 skutterudite thermoelectric thin films were prepared by DC magnetron sputtering. The electrical conductivity, Seebeck coefficient, thermal conductivity, and figure of merit ZT of the samples are characterized in a temperature range of 300 K to 700 K. X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy are obtained to assess the phase composition and crystallinity of thin film samples at different heat treatment temperatures. Carrier concentrations and Hall mobilities are obtained from Hall Effect measurements, which provide further insight into the electrical conductivity and Seebeck coefficient mechanisms. The thermal conductivity of thin film filled skutterudite was found to be much less compared with bulk Yb filled CoSb3 skutterudite. In this work, the 1020 K heat treatment was adopted for thin film post process due to the high degree of crystallinity as well as avoiding reverse heating effect. Thin film samples of different thicknesses were prepared with the same sputtering deposition rate and maximum ZT of 0.48 was achieved at 700 K for the 130 nm thick sample. This value was between half and one third of the bulk figure of merit which was due to the lower Hall mobility.