Thermoelectric properties of thin films of Sb doped Mg2Si1−xSnx solid solutions

Abstract

Polycristalline thin films of Mg2Si1−xSnx (x=0.4, 0.5, 0.6) solid solutions doped with Sb were deposited on SiO2/Si substrates at room temperature by plasma assisted co-sputtering. Independent bias of individual targets of constituent elements enabled to directly control not only the x stoichiometry but also the Sb doping content. The prepared thin films crystallize as a single phase of Mg2Si1−xSnx solid solutions with controlled Sb-doping content between 0 and 3.5at.%. The carrier concentration and electrical conductivity of deposited films first show an increase with Sb doping at low concentration but followed by a decrease when Sb doping concentration is further increased. Despite rather good structural properties, power factor remained low (<3×10−4WK−2m−1), i.e. one order of magnitude lower than that of the bulk material. The results highlight the necessity to improve the crystalline quality of the thin films as well as of a finer tuning of Sb content.