Evaluation of phase and thermoelectric properties of thin film SrSi 2

We firstly prepared SrSi2 thin films on insulating substrates and measured their thermoelectric properties. Thin films of Sr-Si 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 degrees C consisted of amorphous or the metastable CaSi2 structure phase. CaSi2 structure phase was obtained at 600 degrees C irrespective of the pressure and finally stable alpha-SrSi2 (alpha-phase) above 700 degrees C. The films with CaSi2 structure phase had low power factor below 10 mu W m(-1) K-2 for the temperature range between 100 and 400 degrees C. On the other hand, the film with alpha-phase showed p-type conduction and good thermoelectric power factor beyond 700 mu Wm(-1) K-2 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 mu Wm(-1) K-2 at 300 degrees C. The present result shows that alpha-phase is one of the promising candidates as thermoelectric materials. (C) 2019 The Ceramic Society of Japan. All rights reserved.