Barrier photovoltaic effects in PZT ferroelectric thin films

The photoelectric characteristics (independent of ferroelectric polarization) of metal-ferroelectric-metal thin film structures upon exposure to radiation in different ranges of mercury arc lamp spectrum are studied for the Pb(Zr_0.52Ti_0.48)O₃ (PZT) ferroelectrics. The PZT films on platinized silicon substrates were prepared by the sol-gel technique. The relaxations of the short-circuit current and the open-circuit voltage are investigated at different intensities of light with wavelengths in the range 300–1200 nm. It is found that the open-circuit voltage returns to its original value after the cessation of light exposure and a short-term holding of structures in the short-circuited state. The factors responsible for the photocurrent and the photoemf are analyzed, and the conclusion is made that they are predominantly contributed by the barrier photovoltaic effects associated with the presence of the p-n junction in the bulk of films and the Schottky barrier in the film region adjacent to the lower platinum electrode.