Electrical and optical properties of BiFeO3-PbTiO3 thin films

BiFeO
3
-PbTiO
3
(BFO-PT) thin films were fabricated by sol-gel technology. X-ray diffraction pattern reveals the BFO-PT films are in rhombohedral perovskite phase with random orientations. By Pt/BFO-PT/ITO/glass capacitor structure, co-measurement of electrical and optical responses can be achieved. Remanent polarization of 2Pr∼40µC.cm
⁻²
and leakage current density of 2.5×10
⁻⁵
A/cm
²
at 100kV/cm are obtained in BFO-PT/ITO/glass, which are comparable to those in BFO-PT film on Pt/Si. The absorption spectrum shows that the light with wavelength less than 500nm can be absorbed by BFO-PT/ITO/glass, which makes the film presenting in orange-yellow color. The optical band gap of BFO-PT thin film is analyzed and derived to be about 2.9eV for direct band gap and 2.3eV for indirect band gap. It indicates that not only ultraviolet but also visible light may affect the motion of electrons/carriers in BFO-PT films. With this idea, BFP-PT film may be expected in integration in optic-electronics with solar source.