Thin films of thermoelectric compound Mg2Sn deposited by co-sputtering assisted by multi-dipolar microwave plasma

Highlights: → Mg2Sn thin films deposited by plasma co-sputtering, on silicon and glass substrates. → Formation of nano-grained polycrystalline films on substrates at room temperature. → Structural properties vary with target biasing and target-substrate distance. → Formation of the hexagonal phase of Mg2Sn in certain deposition conditions. → Power factor ∼5.0 x 10-3 W K-2 m-1 for stoichiometric Mg2Sn films doped with ∼1 at.% Ag. - Abstract: Magnesium stannide (Mg2Sn) thin films doped with Ag intended for thermoelectric applications are deposited on both silicon and glass substrates at room temperature by plasma assisted co-sputtering. Characterization by scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction confirms the formation of fine-grained polycrystalline thin films with thickness of 1-3 μm. Stoichiometry, microstructure and crystal structure of thin films are found to vary with target biasing and the distance from targets to substrate. Measurements of electrical resistivity and Seebeck coefficient at room temperature show the maximum power factor of ∼5.0 x 10-3 W K-2 m-1 for stoichiometric Mg2Sn thin films doped with ∼1 at.% Ag.