Origin of photoresponse in heterophase ferroelectric Pt/Pb(ZrTi)O3/Ir capacitors

A steady-state short-circuit photocurrent is measured in polycrystalline Pb(ZrTi)O-3(PZT) films with Pb excess. It is found that although the photocurrent is directed opposite to ferroelectric polarization, it is not the depolarization current of the ferroelectric. To explain this, the authors assume that Pt/PZT/Ir capacitor consists of PZT grains and semiconductor PbO phase segregated on PZT grain boundaries during the PZT formation. In such medium, the current across the film flows through channels formed by PbO phase, where an electric field is generated by uncompensated polarization charge of PZT grains. Using this concept, the authors described the experimental dependence of photocurrent on polarization.