Enhanced photocurrent in Pb(Zr0.2Ti0.8)O3 ferroelectric film by artificially introducing asymmetrical interface Schottky barriers

In traditional metal/ferroelectric film/metal structure, it is widely accepted that the photocurrent is originated from two factors: one is the remnant polarization, which produces a depolarization electric field extending over the whole film volume; the other is the top or bottom film/metal interface Schottky barrier. However, the high reflection of opaque or translucent metal electrodes, as well as almost symmetric Schottky barriers in the top and bottom metal/film interfaces result in a low photovoltaic output. In this paper, a transparent indium tin oxide (ITO) electrode was introduced in ITO/Pb(Zr0.2Ti0.8)O3(PZT)/Pt structure, in order to not only make more incident light absorbed by PZT film but also artificially enlarge the Schottky barrier difference between bottom ITO/PZT interface and top PZT/Pt one. The results show that the photocurrent of ITO/PZT/Pt structure is enhanced one order than that of Pt/PZT/Pt structure under the same irradiation of a simulative sunlight (AM 1.5G). The systematic studies present in this paper gave some principles to design ferroelectric film devices in considering higher optical-to-electronic conversion efficiency.