Formation and relaxation mechanisms of the self-polarization in thin ferroelectric films

Upward ferroelectric self-poling in (001) oriented PbZr0.2Ti0.8O3 epitaxial films with compressive strain

“…In fact, upward self-poling (i.e. polarization pointing against substrate surface) was observed in Pb 1-x Zr x TiO 3 films and BaTiO 3 films on (001) SrTiO 3 substrate, [1][2][3][4][5][6] while both upward and downward self-poling (i.e. polarization pointing toward substrate) have been reported in BiFeO 3 films on (001) SrTiO 3 substrate.…”

“…Once the as-grown ferroelectric film has a macroscopic ferroelectric polarization without any external electric field stimuli (i.e. self-poling), 1 the technique and technology for piezoelectric and infrared devices can be simplified.…”

Thickness effect on the structure, grain size, and local piezoresponse of self-polarized lead lanthanum zirconate titanate thin films

“…The origin of the self-polarization in ferroelectric thin films has been discussed in terms of different mechanisms such as Schottky barriers, 22 lead vacancies, 23 mechanical coupling between the film and the substrate, 24 formation temperature of the ferroelectric phase, 25 and some others. When the top and bottom electrodes of a metal/ferroelectric/ metal configuration are made of different materials, trapped charges appear near the bottom ferroelectric-electrode interface leading to a build-in electric field responsible for the self-polarization.…”

The self-polarization effect in Pb(Zr0.50Ti0.50)O3 thin films with no preferential orientation

“…The asymmetrical Schottky barriers and uncompensated electric field appear when the bottom and upper electrodes are made of different materials [3,6]. On the other hand, it may be the presence of a compressive/tensile stress or different thermal expansion coefficients between the film and the substrate and mechanical effects that is responsible for the appearance of a self-polarization state [2]. Although several theoretical [7] models have been proposed to explain the mechanisms of the self-polarization effect, its real nature is still an object of discussion and controversy.…”

“…The observation of a self-polarization state in different systems is frequently associated with various factors such as texture, thickness, different substrates/electrodes and the formation temperature of the ferroelectric phase [2]. This effect has been explained in terms of a space charge associated with the Schottky barriers located at the bottom film-electrode interface [3,4], and also by a mechanical coupling between the ferroelectric film and rigid substrate [5].…”