Direct effect of illumination on ferroelectric properties of lead zirconate titanate thin films

Abstract

Photosensitive ferroelectric materials exhibit various photoferroelectric phenomena due to the strong influence of nonequilibrium charge carriers on polarization and phase transition. These phenomena are essential for a number of applications including photodriven actuators and sensitive photodetectors. In this work, the effect of UV illumination on dielectric and piezoelectric properties is investigated in lead zirconate titanate (PZT) thin films, which are currently the most promising material for microactuator applications. The effective piezoelectric coefficient (d33) and dielectric permittivity (ε) of PZT films are simultaneously measured under a weak ac electric field during illumination with a band gap light (λ=280–400 nm). It is shown that both d33 and ε decrease under UV illumination. The reduction of permittivity, however, is much smaller than that of d33 and demonstrates a much slower time relaxation. The d33 decrease is attributed to the reduction of average remanent polarization under the UV light. Thus a direct effect of the photoactive light on ferroelectric polarization is observed under essentially nondestructive (weak-field) conditions. The origin of the observed effect is discussed along with the possible implications for thin-film devices.

Nanoscale observation of photoinduced domain pinning and investigation of imprint behavior in ferroelectric thin films

“…4,5,9 In those experiments, poling of a capacitor into the negative polarization state with simultaneous UV illumination led to a positive shift of the hysteresis loop, while in our experiments the loops of the negative grains are shifted to negative voltages under UV light. The same situation ͑with opposite sign͒ held for the positive polarization state.…”

Short-circuit photocurrent in epitaxial lead zirconate-titanate thin films

“…It was found that UV light illumination helps the polarization restoration after severe fatigue in polycrystalline PZT films. [21][22][23] This was explained by generation of additional mobile carriers which might play a significant role in a rapid compensation of the polarization charges and by the "erasing" of the charge defects that can act as pinning centers for the ferroelectric domains.…”

Photo-regulated magnetism and photoferroelectric effect in BiFeO3 nanoribbons at room temperature

“…In a previous report, the magnetic field and pressure can slightly change the ferroelectric hysteresis loop, and the relative change of the saturated ferroelectric polarization was less than 20% at room temperature [28,33]. In addition, the minor light-induced change of ferroelectric polarization has already been observed in some ferroelectric compounds [34][35][36][37], however, it has never been reported in (anti/ferro/ferri) magnetic compounds and magnetoelectric ones. In a previous report, the light-induced change of ferroelectric polarization in ferroelectric compounds was explained by trapping of photogenerated charge at domain boundaries to minimize internal depolarizing fields [35][36][37].…”

“…In addition, the minor light-induced change of ferroelectric polarization has already been observed in some ferroelectric compounds [34][35][36][37], however, it has never been reported in (anti/ferro/ferri) magnetic compounds and magnetoelectric ones. In a previous report, the light-induced change of ferroelectric polarization in ferroelectric compounds was explained by trapping of photogenerated charge at domain boundaries to minimize internal depolarizing fields [35][36][37]. The observed remarkable improvement in the ferroelectric polarization of the single-crystalline BiFeO 3 nanoribbons should be attributed to the photogenerated charge (see Supplementary Information for ferroelectric measurement details).…”