Infrared optical properties of BiFeO_3 thin films prepared by chemical solution deposition

摘要

BiFeO_3 thin films have been grown on Pt(111)/Ti/SiO_2/Si substrates by chemical solution deposition. It is shown that the films are polycrystalline by the measurement of X-ray diffraction. The infrared optical properties of BiFeO_3 thin films have been investigated using the infrared spectroscopic ellipsometry in the wavelength range of 2.5 to 12.6 μm. The infrared optical constants of the BiFeO_3 thin films are obtained by fitting the measured ellipsometric spectra data using a three-medium model and a classical dielectric function model. The absorption coefficient of BiFeO_3 thin films is greater than 100 cm~(-1) in total measured wavelength region and greater than 1000 cm~(-1) at the wavelength region above 7.5 μm. It is bigger than that of PbTiO_3, Pb(Zr, Ti)O_3 and (Pb, La)(Zr, Ti)O_3 thin films. It indicates that the BiFeO_3 thin films are excellent candidates for infrared detectors.