Influence of atomic ratio of Mg to Sn on thermoelectric properties of Mg2Sn films

Abstract

The influence of Mg/Sn ratio of on the thermoelectric properties of Mg-Sn films was deeply studied through preparing a series of Mg₂Sn films with different Mg and Sn atomic ratios on SiO₂/Si substrate. The results showed that the phase structure of the deposited Mg₂Sn films varied from a metastable orthogonal phase to a mixture of orthogonal and cubic phase, and then to a highly symmetric cubic phase with increasing [Mg]/[Sn]. Meanwhile, with increasing [Mg]/[Sn], the carrier concentration and electrical conductivity of the deposited films first decreased and then increased, while the carrier mobility and Seebeck coefficient varied in an opposite trend. The cubic Mg₂Sn phase film with [Mg]/[Sn] = 1.94 has the highest Seebeck coefficient and appropriate electrical conductivity, reaching the highest power factor of 3.10 μW cm^-1 K^-2 at 235 °C and figure of merit of 0.059 at 125 °C.