Formation of Mn4 Si7 films by magnetron sputtering and a wide range of their thermoelectric properties

In the paper, films of higher manganese silicide Mn4Si7 have been made and a lot of their properties have been investigated. The composition and structure of the films formed by ion-plasma magnetron sputtering were examined by scanning electron microscopy and X-ray analysis. The temperature dependences of film resistivity (by the four-probe method), of their Seebeck coefficient (by the two-probe method), as well as their Hall constant and optical reflectivity spectra (at room temperature). Their thermoelectric figure of merit, the energy-gap width (0.66 eV), charged-particle density and mobility, etc., were calculated. The properties of the films in the amorphous and polycrystalline phases were compared. The thermopower of the Mn4Si7 film was established to increase by about 6 times during the transition from the amorphous phase to the polycrystalline one. The results obtained indicate that it is possible to use this film in heat wave detectors.