Control of the Polarization of Ferroelectric Capacitors by the Concurrent Action of Light and Adsorbates
journal contributionposted on 18.06.2018, 00:00 by Fanmao Liu, Ignasi Fina, Guillaume Sauthier, Florencio Sánchez, Andrew M. Rappe, Josep Fontcuberta
Ferroelectric perovskites hold promise of enhanced photovoltaic efficiency and photocatalytic activity. Consequently, the photoresponse of oxide ferroelectric thin films is an active field of research. In electrode/ferroelectric/electrode devices, internal charge in the ferroelectric, free charge in the electrodes, and buried adsorbates at interfaces combine to screen the ferroelectric polarization and to stabilize the polar state. Under illumination, photoinduced carriers and photodissociated adsorbates may disrupt the screening equilibrium, modifying the switchable polarization and altering its expected benefits. Here, we explore the photoresponse of BaTiO3 thin films in a capacitor geometry, focusing on the effects of visible illumination on the remanent polarization. By combining ferroelectric and X-ray photoelectron spectroscopy, we discover that photoreaction of charge-screening H2O-derived adsorbates at the buried metal–ferroelectric Pt/BaTiO3 interface plays an unexpected pivotal role, enabling a substantial modulation (up to 75%) of the switchable remanent polarization by light. These findings illustrate that the synergy between photochemistry and photovoltaic activity at the surface of a ferroelectric material can be exploited to tune photoferroelectric activity.
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capacitor geometryswitchable remanent polarizationphotoinduced carrierstune photoferroelectric activityilluminationswitchable polarizationelectrodefilmcharge-screening H 2 O-derived adsorbatesphotoresponseAdsorbates Ferroelectric perovskitesFerroelectric Capacitorsphotovoltaic activityremanent polarizationX-ray photoelectron spectroscopyphotovoltaic efficiencyBaTiO 3photocatalytic activityphotodissociated adsorbatesscreening equilibriumConcurrent Actioninterface