Electrical and optical characterization of PbTiO3/Si heterostructures for applications in optoelectronics

The ferroelectric/semiconductor heterostructures were fabricated by sol-gel deposition of lead titanate (PT) thin films on a single-crystalline p-type Si wafers. The PT films were crystallized by a conventional thermal annealing for 30 min at temperatures ranging from 575 degree(s)C to 675 degree(s)C. Current-voltage and capacitance-voltage characteristics show a hysteresis which can be due to the spontaneous polarization of PbTiO3. The current-voltage characteristics exhibit a diode behavior while the capacitance-voltage exhibits a large memory window, up to 3.5 V, for the films annealed at 600 - 650 degree(s)C. At the illumination with modulated light, a.c. photovoltage was detected on a broad range of wavelengths (0.35 divided by 4 micrometers ) for all samples. The spectral distribution of the photoelectric signal in the UV-Vis- IR domain shows two local maxima. A model is proposed to explain the observed experimental results.