Preparation of Fe-Si thin films by chemical vapor deposition

Fe-Si thin films that can be used as the thermoelectric materials at comparatively higher temperature were prepared by a high frequency induction thermal chemical vapor deposition (CVD). First, biscyclopentadienyliron (ferrocene: Fe(C₅H₅)₂ ) and tetramethylsilane (TMS: Si(CH₃)₄) were used as source materials, and next silane (SiH₄) was used instead of TMS. The films were prepared at substrate temperatures (T_sub) from 1003 to 1373 K, total pressures in the CVD chamber (P_chm) from 1.3 to 6.7 kPa and molar ratios of Si/Fe in the source gas (R_SF/) from 2 to 6. The deposits were strongly affected by the kind of source gas, the molar ratio of Si/Fe in the source gases and the substrate temperatures. The electrical properties such as Seebeck coefficient and electrical conductivity of the films were also measured. The value of Seebeck coefficient of deposits that consisted of Fe₅Si₃ and SiC reached about 45 μVK^-1 at 1000 K, and the value of electrical conductivity was about 1000 Scm^-1 at 1000 K