Evaluation of phase and thermoelectric properties of thin film SrSi2

Abstract

We firstly prepared SrSi2 thin films on insulating substrates and measured their thermoelectric properties. Thin films of SrSi system were deposited on (0001) Al2O3 substrates by radio frequency magnetron sputtering method at various deposition temperatures and under various total deposition pressure. Constituent phases primary depend on the deposition temperature. The films deposited below 600°C consisted of amorphous or the metastable CaSi2 structure phase. CaSi2 structure phase was obtained at 600°C irrespective of the pressure and finally stable ¡-SrSi2 (¡-phase) above 700°C. The films with CaSi2 structure phase had low power factor below 10 ¯W m11 K12 for the temperature range between 100 and 400°C. On the other hand, the film with ¡-phase showed p-type conduction and good thermoelectric power factor beyond 700 ¯W m11 K12 at room temperature. This value is larger than the reported value of (111) one-axis-oriented Mg2Si films prepared by the same deposition process, maximum 130 ¯W m11 K12 at 300°C. The present result shows that ¡-phase is one of the promising candidates as thermoelectric materials.