Photocurrent and dielectric/ferroelectric properties of KNbO3–BaFeO3-δ ferroelectric semiconductors

Abstract

Perovskite oxide (1-x) KNbO3–xBaFeO3-δ (KN–BF; x = 0.00–0.10) ferroelectric semiconductor ceramics are prepared via traditional solid-state synthesis and air sintering. All ceramics show a single perovskite structure and a long-range polarity order by X-ray diffraction (XRD) and Raman spectra, respectively. A minimum optical band gap of approximately 1.82 eV, which is approximately 43% lower than that of pure KN (approximately 3.22 eV), is obtained for the x = 0.10 sample. The ferroelectric behavior of the samples weakens with the increase in BF doping content. The activation energies of the ferroelectric domain and domain wall of 0.93KN–0.07BF ceramics are approximately 0.26 eV and approximately 0.52 eV, respectively, which are ascribed to the conduction mechanism of the first and second ionizations of oxygen, respectively. For the 0.93KN–0.07BF sample, along the positive polarization direction, the short-circuit photocurrent density and open-circuit photovoltage are 11.39 nA cm−2 and 0.217 V under AM1.5 standard sunlight. The results guarantee the feasibility of applying KN–BF ceramics to ferroelectric photovoltaic devices.