Influence of Eu doping on structural and optical properties of BiFeO₃ films deposited on quartz substrates by pulsed laser deposition method

The Bi_1−xEu_xFeO₃ (B_1−xE_xFO, x = 0, 0.03, 0.05, 0.07) films were grown on quartz substrates by pulsed laser deposition. X-ray diffraction analysis indicates the B_1−xE_xFO films exhibit the distorted rhombohedral perovskite structure, and the substitution of Eu into the Bi site. Atomic force microscopy and scanning electron microscopy show that the B_1−xE_xFO films are smooth and uniform. With increasing Eu content, the fundamental absorption edges of B_1−xE_xFO films show red shift. At the wavelength of 720 nm, the refractive index increases and the extinction coefficient decreases with increasing the amount of Eu. The band gap of the B_1−xE_xFO films decreases from 2.694 ± 0.007 to 2.501 ± 0.005 eV with increasing Eu content from x = 0 to x = 0.07, which provides potential application for optoelectronic and photovoltaic devices due to the enhanced photovoltaic conversion ability.