Thin-Film Capacitor M/Pb(ZrTi)O3/M as a Polarization-Sensitive Photocell

A steady-state short-circuit photocurrent of preliminarily polarized submicron capacitors with a polycrystalline Pb(ZrTi)O-3 (PZT) film is investigated under irradiation by light with a wavelength lambda > 0.4 mu m. The structures with different M/PZT interfaces that differ in the leakage current by more than an order of magnitude are found to demonstrate virtually the same value of the photocurrent, which is always directed opposite to the ferroelectric polarization of the PZT film. Although the magnitude of photocurrent is determined by the degree of polarization of the film, the observed photocurrent is not a depolarization current of the ferroelectric film. Therefore, the M/PZT/M capacitor behaves like a polarization-sensitive photocell. Within the proposed theory of a heterophase medium, the dependence of the photocurrent on the magnitude of the preliminary polarization is calculated and proves to be in reasonable agreement with the experimental results.