Preparation of n-type nano-scale MnSi1.7 films by addition of iron

Nano-scale higher manganese silicide (MnSi1.7) film with thickness of about 27 nm is prepared by thermal annealing of a bi-layer Si/MnSix (x < 1.7) at 650 °C. When the thermal annealing time is 25 min, the film is p-type from 300 K to 633 K. By increasing the thermal annealing time to 65 min, the film is still p-type around room temperature but transforms to n-type at high temperatures. The thermoelectric powers at 300 K and 633 K are +116 μV K−1 and −321 μV K−1, respectively. With addition of enough iron to the film, n-type MnSi1.7 film with lower electrical resistivity is obtained. The thermoelectric power reaches to −568 μV K−1 at 533 K. As a result, the thermoelectric power factor of the nano-scale n-type MnSi1.7 film at 533 K is 3.6 × 10−3 W m−1 K−2. This value is greater than that of p-type bulk MnSi1.7 materials.