Experimental study of the built-in field in intergrain channels of thin ferroelectric Pb(Zr,Ti)O$_3$ films

The experimentally measured dependence of the photo-emf on the remanent polarization in thin-film M/Pb(Zr,Ti)O$_3$(PZT)/M capacitors correlates well with the model developed by us for the intergrain photovoltaic effect for films with columnar structure of PZT grains and heterophase intergrain boundaries. In this case, the photo-emf is determined by the depolarization field generated by the uncompensated polarization charge at PZT grain boundaries. It is shown that the magnitude and orientation of the built-in field in an intergrain channel of such PZT films can be derived from measurements of the photo-emf at zero polarization with a sensitivity on the order of a few millivolts.