  We have investigated the thermoelectric and thermal behaviour of Fe-V-W-Al
based thin films prepared using radio frequency magnetron sputtering technique
at different base pressures (0.1 ~ 1.0 X 10-2 Pa) and on different substrates
(n, p and undoped Si). Interestingly, at lower base pressure, formation of bcc
type of Heusler structure was observed in deposited samples, whereas at higher
base pressure, we have noted the development of non-Heusler amorphous structure
in these samples. Our findings indicates that the moderately oxidized Fe-V-W-Al
amorphous thin film deposited on n-Si substrate, possesses large magnitude of
absoulte S ~ 1098 microvolt per kelvin near room temperature, which is almost
the double the previously reported value for thin films. Additionally, the
power factor indicated enormously large values ~ 33.9 milliwatt per meter per
kelvin sqaure near 320 K. The thermal conductivity of the amorphous thin film
is also found to be 2.75 watt per meter per kelvin, which is quite lower
compared to bulk alloys. As a result, the maximum figure of merit is estimated
to be extremely high i.e. ~ 3.9 near 320 K, which is among one of the highest
reported values so far. The anomalously large value of Seebeck coefficient and
power factor has been ascribed to formation of amorphous structure and
composite effect of thin film and substrate.
