Chemical vapor deposition of polycrystalline Fe_3O_4 thin films by using the cyclohexadiene iron tricarbonyl liquid precursor

摘要

Magnetite (Fe_3O_4) thin films are synthesized by chemical vapor deposition (CVD) with the cyclohexadiene iron tricarbonyl Fe(C_6H_8)(CO)_3 liquid precursor. The growth of pure, polycrystalline, and stoichiometric Fe_3O_4 films is confirmed by X-ray diffraction, Raman spectroscopy, time-of-fiight secondary ion mass spectrometry, and conversion electron Moessbauer spectroscopy. At 297 K, the resistivity for 24.8 nm (100 nm) Fe_3O_4 thin film is 17 × 10~(-3) Ωcm (4.2 × 10~(-3) Ωcm), indicating the good electrical quality of the as-deposited layers. Magnetoresistance (MR) up to -2.2% is measured at 297 K at 1.1 T, corresponding to 15% electron spin polarization. A gradual increase of MR is observed at low temperature. In particular, the observed MR = -4.4% at 120 K (at 0.8 T) is attributed to an intrinsic enhancement of the electrons spin polarization up to 21.5%.