The thermoelectric properties of the Mg2(Sn,Si) films by magnetron sputtering with different microstructure

The Mg-2(Si,Sn) solid solutions films have been deposited on single crystalline Si(111) substrates under temperatures from 130 to 400 degrees C by magnetron sputtering using a Mg-Si-Sn alloy target. The phase components, microstructures and the thermoelectric properties of these films were investigated. It is indicated that the films deposited under lower temperature ( <= 300 degrees C) possess a cubic anti-fluorite structure phase and their structures transform into orthorhombic and hexagonal with the increasing temperature to 400 degrees C. Meanwhile, the tetragonal structure metal Sn phase occurs on samples deposited under temperatures of 350 degrees C and 400 degrees C. Furthermore, the film deposited under 350 degrees C is composed of cubic anti-fluorite structure and orthorhombic structure phase, and possesses the highest absolute value of Seebeck coefficient and the highest electrical resistivity. On the other hand, the film deposited under 130 degrees C which is composed of only cubic anti-fluorite structure possesses the highest power factor at all measured temperature due to higher absolute value of Seebeck coefficient and lower electrical resistivity. It is suggested that the Mg-2(Si,Sn) solid solutions film with cubic phase structure has higher power factor than that with orthorhombic and hexagonal phase structure.