Thermoelectric performance of Fe₂V_0.9W_0.1Al thin films deposited on n-type Si substrates

Abstract

Fe2V0.9W0.1Al thin films are prepared on n-type Si substrates by means of radio-frequency magnetron sputtering with varied substrate temperatures from 743 – 1043 K, then subsequently annealed for one hour in vacuum at 1043 K. The thin films deposited at 1043 K are chemically degraded, exhibiting a low Seebeck coefficient, –65 µVK–1, at 330 K. On the other hand, the films deposited at 943 K possess –100 µVK–1 in Seebeck coefficient at around 330 – 350 K, which is very similar to the Seebeck coefficient of the bulk W-substituted Fe2VAl that possesses well-ordered L21 structure. The maximum power factor of 1.6 mWm–1K–2 was obtained for the sample deposited at 943 K. Accordingly, with the thermal conductivity of 3.5 Wm-1K-1, the figure of merit reached up to ZT = 0.16, which is comparable with Fe2V0.9W0.1Al of bulks and two times larger than that of the thin films of Si-substituted Fe2VAl.