Abstract:The Mg₂Si thermoelectric thin films were fabricated by radio frequency magnetron sputtering with the Mg-Si binary composite target. The effects of sputtering power, vacuum annealing temperature and annealing time on the qualities of Mg₂Si thin films were studied to find out the optimal preparation process. The properties of the thin films were tested by scanning electron microscope (SEM), X-ray diffraction (XRD), Hall effect tester, film Seebeck coefficient measurement system. As showed in energy dispersive X-ray spectrum of the Mg₂Si thin film profile, Mg and Si in the thin films distribute uniformly and the mole ratio of Mg to Si in thin films is about 2:1, which is consistent with the mole ratio of Mg₂Si phase. XRD results show that the sputtering power, vacuum annealing temperature and annealing time have effects on the film quality. The test results of Hall measurement and Seebeck coefficients measurement reveal that all the samples are n-type. The Seebeck coefficients are in the range of -278.648- -483.562 μV/K, and the electrical conductivities are in the range of 1.240-46.926 S/cm. Among all, the Mg₂Si thin film deposited with 120 W and annealed at 400 ℃ for 3 h have the highest power factor of 0.364 mW/(m？K²).

Key words: Mg₂Si thin film; radio frequency magnetron sputtering; optimal preparation process; thermoelectric properties